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Introduction
Nitric Oxide
           Introduction
           Nitric Oxide Synthesis
           Physiological (Beneficial) Pathways of Nitric Oxide
           Pathological (Detrimental) Pathways of Nitric Oxide
           Causes of Elevated Nitric Oxide Levels
                 Prolonged or Repetitive Immune Activation
                 Hyper-Excitement of NMDA Receptors
                 Hyper-Excitement of Vanilloid Receptors
                 Hyper-Excitment of Muscarnic Acetylcholine Receptors
                 Toxicity
                 Stress or Psychological Trauma
                 Physical Trauma
                 Ionising Radiation Exposure
                 Pre-Existing Autoimmune Disease or Inflammatory Condition
                 Genetic Predisposition to Elevated Nitric Oxide Levels
                 Low Tissue Oxygenation and Capillary Budding
                 Psychological Stress or Trauma
           Too Low Nitric Oxide Levels? David Whitlock's Hypothesis
Superoxide
           Introduction
           Formation of Superoxide
           Genetic Predisposition to Elevated Superoxide Levels
           Superoxide Dismutase (SOD)
Peroxynitrite
           Introduction
           Formation of Peoxynitrite
           Other Reactive Nitration Species (ROS) formed from Peroxynitrite
           Pathological (Detrimental) Pathways of Peroxynitrite
           Antioxidant Protection against Peroxynitrite
Balance between Free Radicals and Antioxidants
Dr Martin Pall's Peroxynitrite Protocol
           Preventative Measures
           Treatment Protocol
Dr Paul Cheney's Peroxynitrite Protocol
           Methods of reducing elevated Peroxynitrite levels
           Methods of Reducing Elevated Peroxynitrite & Superoxide Levels
           Methods of Blocking Nitric Oxide Production
           Other Methods
           General Comments on Dr Paul Cheney's Hypothesis on Peroxynitrite
Other Protocols
           Dr Jacob Teitelbaum's Peroxynitrite Protocol
           Dr Gareth Nicolson's Peroxynitrite Protocol
           Dr Neboysa Petrovic's Peroxynitrite Protocol
Markers and Tests for Peroxynitrite

Introduction:
Dr Martin Pall has hypothesised in his book 'Explaining "Unexplained Illnesses": Disease Paradigm for Chronic Fatigue Syndrome, Multiple Chemical Sensitivity, Fibromyalgia, Post-Traumatic Stress Disorder, Gulf War Syndrome, and Others' (2009) that the NO/ONOO- (Nitric Oxide) cycle may be a significant factor in some cases of CFS, FM, Multiple Chemical Sensitivities (MCS) (see the Effects of Toxicity page for more information), Post Traumatic Stress Disorder (PTSD) and perhaps even Autism. He suggests that the elevated Nitric Oxide and Peroxynitrite levels in these conditions is a shared root cause or factor, which is also comorbid in a large number of other well-accepted diseases, for example viral related illnesses, allergies and autoimmune conditions. This might also explain how some sufferers of one of these conditions may develop multiple instances of other inflammatory conditions concurrently, as they share a root driver. Autoimmune diseases such as Lupus and Rheumatoid Arthritis, are reported to have elevated iNOS activityand peroxynitrite, NF-kB and cytokine elevation at the sites of the autoimmune-related inflammation. These factors shall be examined in this article.
In these illnesses, short term stressors such as viral or bacterial infection, physical or psychological trauma or exposure to various toxic chemicals are thought to raise the Nitric Oxide (oxidant) levels in the body, exaccerbating their symptoms. The elevated Nitric Oxide levels react with Superoxide in the body, a byproduct of a number of bodily processes, to form the very harmful rogue oxidative species Peroxynitrite. The formation of Peroxynitrite causes a wide variety of oxidative damage to the body, particularly to mitochondrial enzymes, membranes and also hemoglobin, as well as destroying the protective antioxidant enzyme Superoxide Dismutase (SOD) (and other mechanisms for stimulating Superoxide production), thereby allowing Superoxide levels to build up, causing more of the Nitric Oxide to react with this Superoxide, thereby perpetuating or worsening the condition by producing more Peroxynitrite.
Raised Superoxide levels through physical or mental overexertion can also trigger increased inflammation by reacting with Nitric Oxide as well as burning up our mitochondrial enzymes and membranes, impairing mitochondrial function. The increased inflammation also makes it harder for the mitochondria to repair effectively, creating slow recovery periods from overexertion, even when the patient rests for days or weeks at a time.
Pall argues that therapy should focus on down-regulating the NO/ONOO- cycle biochemistry rather than on treating symptoms. He has recommended that nutritional/mineral support and individual and full-spectrum antioxidant preparations that together may assist in down-regulating this NO/ONOO- cycle mechanism are to be considered a sensible approach as part of an overall treatment programme.
The intensity of the Nitric Oxide and Peroxynitrite cycle does appear to vary in the patients of the above cases, but it does appear to be a factor in the overall illness of each respective person to some degree. It may be a primary driver or cause in one patient, and play a secondary part compared to other primary causes, e.g. heavy metal toxicity, in the next patient. In some phases of an illness, inflammation can play a smaller part secondary to other factors, and in other phases it may play the dominant role. Symptoms of inflammation vary, depending on where exactly in the body the inflammation is and what the exact nature of it is. Nervous system aberrations and cognitive disability ('brain fog') often point to excessive inflammation and/or excitotoxicity in the brain.
Some summaries of Martin Pall's Peroxynitrite hypothesis can be found at the links below. The final link is probably the most technical and comprehensive read, which is presumably a summary of Pall's book. BlackSpy recommends purchasing Pall's book of course..
www.allergyresearchgroup.com/Martin-Pall-NO-ONOO-sp-42.html
www.chronicfatiguetreatments.com/wordpress/treatments/interview-with-dr-martin-pall
www.immunesupport.com/library/showarticle.cfm?id=8071&T=CFIDS_FM
www.immunesupport.com/library/showarticle.cfm?id=8075
www.geocities.com/tenthparadigm/PallBio.html
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Nitric Oxide (NO):
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Introduction:

Nitric Oxide, a.k.a. Nitrogen Monoxide or NO, is a important signalling molecule in mammals, including humans. Most other signalling molecules in the body are non-gaseous, which makes NO quite unusual as it is a gas at room or body temperature. It is both an oxidising and reducing agent, depending on what molecules or ions it is reacting with. In other words it is both a free radical (pro-oxidant) and antioxidant.
NO has a very short half life of around 1 second, and only exists for a few seconds. Nitric Oxide (NO) is not the same as Nitrous Oxide (N2O), a general anaesthetic and fuel for dragsters. Another oxide form of Nitrogen is Nitrogen Dioxide (NO2).
NO is involved in both physiological and pathological processes, depending on its concentration and precise conditions. It is thus anti-inflammatory and pro-inflammatory. These two properties of NO are examined below.
http://en.wikipedia.org/wiki/Nitric_oxide
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Synthesis of Nitric Oxide:
NO is synthesised by the reduction of the amino acid Arginine and O2 by various Nitric Oxide Synthase (NOS) enzymes and also by the reduction of inorganic nitrate.

There are three types of Nitric Oxide Synthase (NOS enzymes):
- Neuronal NOS (nNOS) - is found in fairly constant levels (according to cell type) in many neurons in the brain, spinal cord and peripheral nervous system; and also in many other types of cells in the body.
- Endothelial NOS (eNOS) - is found in fairly constant levels (according to cell type) in the endothelial cells that line the blood vessels; and also in many other types of cells in the body. In this role, eNOS acts as a vasodilator.
- Inducible NOS (iNOS) - is found only in very small quantities unless it is induced, typically under inflammatory (oxidative) conditions (e.g. shock, toxicity or infection). iNOS also plays a role in modulating vasoconstrictor responses in hypertension. iNOS induction is considered to be part of the emergency pathway of NO.
http://en.wikipedia.org/wiki/Nitric_oxide_synthase
Both nNOS and eNOS are Calcium dependent, producing no NO unless Ca2+ is present. The cytoplasm of these cells typically have low levels of Ca2+. Cellular Calcium levels are tightly regulated. However, any pathway that increases cellular/cytoplasmic Calcium levels will also increase NO production and NO levels. Also, any pathway that induces iNOS, under immune system inflammatory conditions, will also increase NO production and NO levels.
As the nNOS and eNOS enzymes in the cells are not fully saturated/utilised at any one time in Nitric Oxide and Citrulline production from L-Arginine, then increasing the L-Arginine concentration in the cell above normal will likely increase the rate of NO production. Thus it is inadvisable for individuals with elevated NO levels to consume L-Arginine rich foods or take L-Arginine supplements to push their L-Arginine levels above normal as it will likely worsen one of the root causes of their condition.
Tetrahydrobiopterin (BH4) is one of the cofactors involved in NO production. BH4 is a form of reduced Biopterin and is also an protective mechanism against the free radicals produced by cellular inflammation (i.e. Neopterin). Neopterin, BH4 and Biopterin are discussed on the Immunity page in the Pterins section.
When a cellular NOS enzymes have limited BH4 or L-Arginine, they may produce Superoxide (O2-) instead of NO. L-Arginine levels tend to be relatively low (sub-normal) in those with elevated NO and/or peroynitrite levels, as their L-Arginine body pools have been used up in NO production. Superoxide has most of the same properties of NO as a messenger molecule. Producing Superoxide outside of the relative safety of the inner mitochondrial membrane may result in the NO/ONOO- cycle being exacerbated, i.e. the NO present in the cell reacting with the Superoxide to form the harmful Peroxynitrite (ONOO-).
BH4, in its role as antioxidative protection inside a cell reacts with Peroxynitrite and is oxidised to Biopterin. Oh course, BH4 can and is also oxidised by Neopterin, an inflammatory cytokine, which may or may not itself be stimulated by the presence of Peroxynitrite - a viral or other infection, other sources of free radicals, chemical sensitivity, and/or an allergic/intolerance response may also be responsible potentially. BH4 and Biopterin levels can be measured as discussed below. It is likely that this is one pathway for Peroxynitrite formation in those with excessive levels.
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Physiological (Beneficial) Pathways of Nitric Oxide:
In low concentrations, NO is a beneficial messenger molecule in the body. Appropriate NO levels are important in protecting organs such as the liver from ischemic damage or ischemia, that is, damage caused by a restriction in blood supply. NO is also used as an antimicrobial agent by certain types of White Blood Cells.
'Nitric oxide (NO) protects the heart, stimulates the brain, kills bacteria, helps prevent blood clots that are the cause of most heart attacks and strokes, enhances oxygen delivery to tissues, and helps regulate blood pressure and blood flow to different organs. It is present in most living creatures and made by many different types of cells. It was a sensation when it was discovered that this simple, common air pollutant,-which is formed when nitrogen burns, for instance in automobile exhaust fumes-could exert so many important and life saving functions in our body.'
www.chelationbysuppository.com/faq_chelation_suppository.html
- Role as a Messenger Molecule (Neurotransmitter) [nNOS]:
NO is highly reactive - as well as being an oxidising agent, it can also act as a reducing agent, reacting with O2, Chlorine, Bromine and other species. It diffuses well across cell membranes. However, it has a chemical lifetime of only a few seconds at the most. These attributes make it ideal as a inter- and intra-cellular signalling molecule (neurotransmitter).
- Nitrosylation and Other Protein Conversion Applications:
NO is also involved in the process of Nitrosylation, i.e. the addition of a Nitroysl (N=O) group to a protein. This is an important biological application of NO. Thus it hels to convert thiol groups (S-H), including Cysteine residues in proteins, to form s-nitrosothiols (RSNOs). S-Nitrosylation is an important mechanism for dynamic, post-translational regulation of most or all major classes of protein. NO is involved in a number of other protein conversion pathways.
- Role as Vasodilator and Vascular Regulator [eNOS]:
NO is one of the main Endothelium-Derived Relaxing Factors (EDRF). These are factors that are released by the endothelium (interior cell wall lining of blood vessels) to help induce smooth vascular (blood vessel) muscle relaxation and increased blood flow. In other words one of its functions is as a vasodilator. Vasdilators enlarge the blood vessels, increase blood flow and reduce blood pressure.
http://en.wikipedia.org/wiki/Endothelium-derived_relaxing_factor
Nitric Oxide activates the heterodimeric enzyme soluble guanylyl cyclase by binding to it. Guanylyl Cyclase is known as the Nitric Oxide Receptor. Activated Guanylyl Cyclase enables the production of cyclic GMP (cGMP). Cyclic GMP in turn activates and regulates the enzyme G-kinase. G-kinase modifies proteins in the cell through phosphorylation, including myosin light chain phosphatase, resulting in the deactivation of myosin light-chain kinase, and subsequently the dephosphorylation of the myosin light chain, causing smooth muscle relaxation.
NO production tends to be elevated in those individuals who live at altitude, as its vasodilation properties (when generated by eNOS) help to increase blood flow and hence increased chance of oxygenation in the lungs, thus preventing hypoxia. NO is also involved in the production of male erections through its vasodilation properties. Erectile dysfunction may result from too much vasoconstriction in the penis. Viagra (Sildenafil citrate) stimulates erections by enhancing signalling through the NO pathway in the penis (cGMP generation). Nitroglycerin and Amyl Nitrate serve as vasodilators (esp. of the sphinctre) because they are converted to NO in the body.
NO contributes to blood vessel homeostasis by inhibiting vascular smooth muscle contraction (vasoconstriction) and growth, platelet aggrgation and leukocyte (white blood cell) adhesion to the endothelium (blood vessel lining). This is why impaired NO pathways are often noted in individuals with atherosclerosis, diabetes and hypotension (elevated blood pressure). A high salt (NaCl) intake has been shown to attenuate NO production but without controlling bioavailability.
- Role as Antimicrobial Agent in the Immune System [iNOS]:
NO is generated as part of the normal immune system response by White Blood Cells known as Phagocytes (that ingest their targets) - including monocytes, macrophages and neutrophils. Phagocytes have both inducible and inhibitory enzymes to control NO. NO secreted as an immune system response uses NO's free radical properties and it is toxic to bacteria, causing the bacteria DNA damage and degradation of their iron sulphur centres. Many pathogenic bacteria have however developed NO resistance. Inflammatory cytokines are also active in inducing iNOS.
Phagocytes also consume O2 and use it to generate O2-, which is used by the NADPH oxidaze enzyme to generate a variety of different oxidants that are used to kill the fungi and bacteria that they ingest. This can be a substantial source of O2- and other oxidants in infected tissues. An increase in O2- production may thus result from the immune system's inflammatory response.
Reactive Nitrogen Species (RNS) is a family of antimicrobial molecules derived from NO produced via the enzymatic activity of inducible Nitric Oxide Synthase 2 (NOS2) gene. NOS is expressed in the liver by macrophages (WBCs) and is inducible by a combination of lipopolysaccharide (a.k.a. LPS - found on the outer membrane of gram-negative bacteria, acting as endotoxins) and certain cytokines.
http://en.wikipedia.org/wiki/Reactive_nitrogen_species
As stated above the NO produced by the iNOS inside Phagocytes is an emergency pathway of the body, active during times of infection and shock etc. In this role, the NO acts to modulate the vasoconstriction response of the blood vessels to Superoxide production (also from the Phagocytes), producing Peroxynitrite. iNOS is known to cause some increased vascular permeability. Increased iNOS activity is associated with hypertension, which is itself often a product of increased Superoxide production. Please see the Superoxide Synthesis section for more information.
'Evaluation of iNOS-dependent and independent mechanisms of the microvascular permeability change induced by lipopolysaccharide.' Fujii et al. 2000.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1572034
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Pathological (Detrimental) Pathways of Nitric Oxide:
Some of the pathological effects of elevated NO radicals are listed below. There are other mechanisms of elevated NO levels but they are not fully understood at this time.
Chronic expression of NO is associated with various carcinomas (cancers of the epithelial cells) and inflammatory conditions such as juvenile diabetes, Multiple Sclerosis (MS), Arthritis and Ulcerative Colitis (according to a 1997 study).
- Peroxynitrite Formation:
The direct toxicity of endogenous NO is considered to be modest. However, its toxicity level increases greatly when it reacts with Superoxide (O2-), with which it readily and rapidly combines. The higher the levels of NO present, the greater the risk of it reacting with Superoxide to form Peroxynitrite.
NO is also an oxidising free radical in its own right, and causes some oxidative stress on the body. In high concentrations, NO is a harmful oxidising agent that can cause excessive oxidative stress on the body's membranes and tissues. Sustained levels of NO production can result in direct tissue toxicity. However, the majority of the pathology of elevated NO is through Peroxynitrite formation.
As mentioned above, NO can protect organs such as the liver during Ischemia (damage caused by the restriction of blood supply to an organ). . NO can however contribute to reperfusion injury, a type of cellular injury occurs when blood returns to an area that had previously had its blood supply constricted, by increasing inflammation and oxidative damage. In such circumstances, NO reacts with the respiration intermediary product Superoxide to form the damaging oxidant molecule Peroxynitrite. Peroxynitrite by contrast is significantly more toxic than NO.
- Oxidation of Hemoglobin:
http://herkules.oulu.fi/isbn9514268512/html/i231674.html
'Nitric oxide forms complexes with transition metal ions, including those regularly found in metalloproteins. The main trap for NO is oxyhemoglobin, which binds NO faster by five to six orders of magnitude than oxygen. The reaction with haemoglobin produces nitrate and methaemoglobin (met-Hb)...Other NO-sensitive metalloproteins are NOS, cytochrome P450 (22), ferritin, ceruloplasmin, myoglobin, cyclo-oxygenase, catalase, ribonucleotide reductase and several components of the mitochondrial respiratory chain. These reactions have wide implications for the physiologic and toxic effects of NO.'
As NO levels in the body become elevated, NO increasinly oxidises Hemolglobin. In a healthy individual, approximately 1% of total Hemoglobin has been oxidised (mainly by NO). However, in individuals suffering from oxidative stress, on account of increased NO levels, the Methemoglobin levels may be significantly higher. The oxidation of Hemoglobin (Haemoglobin) to Methemoglobin, a form that cannot bind with O2 is discussed on the Tissue Oxygenation and CFS page. Other hemo-proteins are also discussed on that page in the Porphyrins and Heme section.
- Inhibition of Mitochondrial Enzymes:
NO can inhibit (oxidise) the last enzyme in the electron transport chain of mitochondrial function, known as Cytochrome C Oxidase or Complex IV.
http://en.wikipedia.org/wiki/Cytochrome_oxidase
Both NO and Peroxynitrite can oxidise one of the Iron-Sulphur protein-based enzymes in the Krebs cycle (Citric Acid cycle), known as Aconitase. This is discussed below in the Peroxynitrite section.
Both of these two enzymes are important for mitochondrial function and the generation and transport of ATP (i.e. energy production) inside every cell in the body. Pall argues that the Aconitase enzyme has a lower activity in CFS patients, and perhaps this is why, because of excessive NO/ONOO- levels.
- Formation of Dinitrogen Trioxide:
NO also reacts with Nitrogen Dioxide (NO2), presumably in lieu of reaction with Superoxide, to form Dinitrogen Trioxide (N2O3). N2O3 is another type of Reactive Nitrogen Species (RNS). This reaction is reversible. All nitrogen oxides are good oxidising agents.
NO + NO2 = N2O3
- Excessive Cyclic GMP Formation:
Excessive cyclic GMP formation also plays a part in the pathological path for NO.
- Vascular Collapse in Septic Shock
Elevated NO levels can contribute to vascular (blood vessel) collapse associated with septic shock.
http://en.wikipedia.org/wiki/Nitric_oxide
http://en.wikipedia.org/wiki/Shock_(circulatory)#Signs_relating_to_different_causes
http://www.accessscience.com/qanda.aspx?id=4898&term=Cardiovascular+system
- S-Nitrosothiol Formation on Proteins:
Whilst NO is thought to be implicated in S-Nitrosothiol formation on proteins of cells, the overall picture is unclear, as Superoxide and Peroxynitrite act to oxidise and destroy these structures.
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Causes of Elevated NO Levels:
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Prolonged or Repetitive Immune Activation:
As mentioned in the introduction to this page, elevated NO can arise by a number of pathways. The most relevant to CFS, ME and Fibromyalgia patients is probably the infection route, that upregulates NO, production. According to Pall, in CFS and ME patients this is mostly commonly viral infection(s) and bacterial infection(s), less commonly protozoan infections such as toxoplasmosis. In Fibromyalgia patients, viral infections are most common stressors, with bacterial infections usually playing a secondary role if relevant.
Over successive infections, NO production may become increasingly elevated, of course mediated by a large number of other biochemical and psychological factors. This is perhaps why infections are a major trigger in causing CFS, as NO levels in an already impaired body with lowered Glutathione levels and elevated toxicity levels, can result in excessive Peroxynitrite formation. Some treatments for elevated NO and ONOO- levels may thus be geared towards eradicating any remnants of the triggering infection or any new infections or cumulative infections, and also boosting and taming the immune system, perhaps in conjunction with avoiding anything that causing excessive inflammation, such as problem foods.
Raised Neopterin levels, a pro-inflammatory and oxidative cytokine, as well as TNF-alpha, may lead to Inducible Nitric Oxide Synthase (iNOS) gene expression and Nitric Oxide synthesis, based on studies in rat vascular smooth muscle cells (Hoffmann et al., 1998).
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Hyper-Excitement of NMDA Receptors:

L-Glutamate (or Glutamic acid) is the most important excitatory neurotransmitter in the brain and plays an important part in brain chemistry. It is released by many different types of neurons and stimulates other neurons at the synapses. The excitatory neurotransmitters act to stimulate the next neuron (i.e. postsynaptic neuron) to fire an electrical impulse.
Inhibitory neurotransmitters tend to inhibit firing of neurons. The most important of these is GABA, which is synthesised from Glutamine in the presence of Active Vitamin B6 (P5P). GABA is examined more on the Adrenal and Endocrine System page. Taurine is another, which performs many vital functions in the body, including nutritional metal transport into the cells. Taurine is examined in more detail on the Nutritional Deficiencies page.
GABA and Glutamate levels are balanced in the brain both in terms of absolute concentrations and relative ratios in a healthy individual. A P5P deficiency can thus result in an elevated Glutamate to GABA ratio in the brain and elevated levels of excitotoxicity. Excitotoxicity is the term used when the levels of the excitatory neurotransmitters are too high, at which point the level of neuronal activation or induced firing of neurons become neurologically damaging. Excitotoxins, specifically free glutamate, and the neurological damage they can cause, are examined on the Excitotoxins section on the Nutritional page, with respect to Glutamate and MSG.
N-methyl-D-aspartate (NMDA) receptors in the nervous system system are found in various nerve cells or neurons in the brain, spinal cord and peripheral nervous system. They are also found in some non-neuronal cells. They are stimulated by the excitatory neurotransmitters,i.e. the amino acid Glutamate (Glutamic acid) and Aspartate (Aspartic acid). There are four main classes of receptor that are stimulated by excitatory neurotransmitters. These are the NMDA receptors, AMPA receptors, kainate receptors and metabotropic receptors. The NMDA receptors are of interest here in their role in Nitric Acid production. Whilst the NMDA receptor was thus named because it is the only receptor to repond to NMDA (a synthetic, non-naturally occuring excitatory substance), this is not the biological function of these receptors (as NMDA is not actually produced in the body). The primary biological function of NMDA receptors is to respond to Glutamate and Aspartate. NMDA receptors are also stimulated by the amino acid Glycine and by polyamines. There are in fact 4 structurally distinct types of NMDA receptor, rather than one generic type. Aspartate fulfils other functions than acting as an excitatory neurotransmitters and it is involved in the Krebs cycle for energy production in the mitochondria.
Dr Martin Pall has stated that a state of hyper-excitement of the postsynaptic cellular NMDA receptors by the presence of elevated Glutamate and Aspartate levels (i.e. excitotoxicity) and/or insufficient GABA and Taurine levels, results in the receptor opening up a channel in the cell membrane, and allowing an influx of Calcium (Ca2+) ions and an egress of Potassium (K+) ions. NMDA receptor over-activation can thus also result in depleted postsynaptic cellular Potassium levels. The influx of Calcium ions into the cells stimulates the nNOS and eNOS Nitric Oxide Synthase enzymes, leading to increased Nitric Oxide production in these postsynaptic cells. Pall suggests that a second Glutamate receptor, e.g. AMPA or kainate receptor, adjacent to the DNMA receptor, may indirectly act to increase the sensitivity of the NMDA receptor to stimulation. nNOS is usually found in muc high concentrations in neurons than eNOS, so that most of the NO production from NMDA receptor activation in such cells is thought to be due to nNOS.
Pall suggests NMDA receptors may perhaps increase Peroxynitrite levels directly, although there is at present no evidence to suggest this, the mechanism for elevated Peroxynitrite being a consequence of elevated NO levels in the presence of presumably elevated Superoxide levels.
Pall is uncertain as to whether NMDA stimulation by Glycine or polyamines plays any role in multi-system illnesses and the NO/ONOO- cycle.
Pall speculates that the documented mechanism of NO (in the learning and memory process) to act as a retrograde messenger in the brain, increasing the long-term potentiation of receptors, diffusing from the postsynaptic cell to the presynaptic cell and next acting to stimulate the release of Glutamate may also act as another potential factor in NMDA receptor overstimulation, as it may create a vicious circle of further NO production and Glutamate release.
'Possible involvement of nitric oxide in NMDA-induced glutamate release in the rat striatum: an in vivo microdialysis study.' Mikhail B. Bogdanov and Richard J. Wurtman. 1996.
Pall also speculates that Peroxynitrite's effect on lowered mitochondrial function (discussed below) including lowered ATP production may have a knock on effect on the NMDA receptors, which become more hypersensitive to stimulation when ATP levels are low. The absence of ATP creates a lowered electrical potential across the outer (plasma) membrane of the cell, which causes the Magnesium (Mg2+) ions to diffuse much more easily from the NMDA receptor site, resulting in these NMDA receptor sites being much more sensitive to stimulation by Glutamate and Aspartate. This may add to the vicious circle of the NO/ONOO- cycle.
The role of NMDA overactivation in the NO/ONOO- cycle may of course vary between patients of CFS, Fibromyalgia, MCS and GWS etc, as does the role of the NO/ONOO- cycle. Pall believes that it is an important trigger mechanism in (the perpetuation of) these conditions. In MCS, Fibromyalgia and CFS, there are studies reporting improved symptoms in the chronic phase in response to NMDA antagonists. Magnesium, an NMDA antagonist, is well documented as being useful in the treatment of these conditions, and is frequently chronically deficient in patients of such conditions.
According to Pall, NMDA receptor stimulation is documented to cause an increase in iNOS activity, NF-kB activity and the synthesis of inflammatory cytokines in the immune system, although it is unclear whether this is a direct mechanism or simply a result of increased NO production (which could equally derive from other NO generating causes).
Pall states that excessive NMDA receptor stimulation is known to play important roles in several neurodegenerative disorders including Parkinson's Disease, Alzheimer's Disease, Amyotrophic Lateral Sclerosis (ALS or Lou Gehrig's Disease) and AIDS-related Dementia. Brain damage involving NMDA receptor overstimulation has been found in a number of the most important diseases of the brain. Pall suggests that a drug for treating Alzheimer's Disease, called memantine, a known inhibitor (antagonist) of NMDA receptors, is additional evidence of this important role that NMDA receptors play in the condition.
Pall has suggested that the toxicity stressors of Mercury, Hydrogen Sulfide and/or Carbon Monoxide poisoning play a part in the intiation of Multiple Chemical Sensitivies (MCS), and that their toxic responses on the body are greatly lowered by NMDA antagonists, implying that these toxins render NMDA receptors to be more sensitive or to be overstimulated. The original stimulation of the NMDA receptor may have been a toxin (in particular organic solvents), a psychological event, or even the party drug Ketamine, but once the pattern of increased NO production and NMDA stimulation is established, then even if the original stressor is removed, the pattern has taken on a life of its own and requires other methods of intervention to break of the cycle.
An article 'Fibromyalgia, Excessive Nitric Oxide/Peroxynitrite and Excessive NMDA Activity' by Martin Pall can be read at the link below. NMDA receptor over-activation, as well as other aspects of the NO/ONOO- cycle are examined in more detail in Pall's book.
http://herkules.oulu.fi/isbn9514268512/html/i231674.html
http://en.wikipedia.org/wiki/NMDA_receptor
'The NMDA receptor (NMDAR) is an ionotropic receptor for glutamate (NMDA (N-methyl D-aspartate) is a name of its selective specific agonist). Activation of NMDA receptors results in the opening of an ion channel that is nonselective to cations. This allows flow of Na+ and small amounts of Ca2+ ions into the cell and K+ out of the cell.'
http://en.wikipedia.org/wiki/NMDA
'NMDA (N-methyl-D-aspartic acid) is an amino acid derivative acting as a specific agonist at the NMDA receptor, and therefore mimics the action of the neurotransmitter glutamate on that receptor. In contrast to glutamate, NMDA binds to and regulates the above receptor only, but not other glutamate receptors. NMDA is a water-soluble synthetic substance that is NOT normally found in biological tissue. It was first synthesized in 1960s. NMDA is an excitotoxin; this trait has applications in behavioral neuroscience research.'
Magnesium supplementation/availability helps to counteract the influx of Ca2+ ions from NMDA stimulation and thus lower the amount of NO released by NMDA receptor stimulation. Zinc also helps to make the NMDA receptor polarisation more difficult.
The algae Spirulina is often recommended by practitioners as a good source of protein, nutrients and Vitamin B12 as well as being an excellent Peroxynitrite scavenger. There is a potential downside in that it is relative high in Aspartic Acid and Glutamic Acid. However, if taken in moderation, the overall effect relative to the NO/ONOO- cycle will be a beneficial one rather than a detrimental one. Please see the Nutritional Deficiencies page for more information.
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Hyper-Excitement of Vanilloid Receptors:

The Vanilloid Receptors in the body respond to vanilloids as well as acidic pH, heat etc. Vanilloids are compounds that contain a functional vanillyl group. Examples of vanilloids include vanillin, vanillic acid, homovanillic acid, Vanillylmandelic acid (VMA) and capsaicin.
http://en.wikipedia.org/wiki/Vanilloid
Natural vanilla flavour contains a large number of different compounds (incuding vanillin), and synthetic forms in food contain just laboratory synthesised vanillin.
VMA is a metabolite of Vitamin B2 and B3 metabolism, as well as the adrenaline and noradrenaline pathway. Excessive levels of the 'stress' neurotransmitters adrenaline and/or noradrenaline (norepinephrine) levels over a period of time may result in elevated VMA levels - high VMA levels may thus be an indicator of this. Please see the Hormone and Neurotransmitter Dysfunction page for more information on VMA and Homovanillic acid.
Capsaicin is the 'heat' in hot chilli peppers and other capsicum peppers.
According to Dr Julius Anderson, when the Vanilloid receptor is stimulated, it opens up channels in the cell's plasma membrane, which allows Calcium ions to flow into the cell. Thus influx of Ca2+ ions increases Nitric Oxide synthesis. Vanilloid receptor stimulation has been demonstrated to lead to NMDA receptor stimulation. Many vanilloid-receptor-containing neurons release glutamate as their neurotransmitter, leading in turn to stimulation of NMDA receptors in the postsynaptic neuron.
Pall believes that the overstimulation and overactivity of the vanilloid receptors is a factor in Multiple Chemical Sensitivities (MCS) cases. Excessive vanilloid activity has also been documented in Fibromyalgia patients.
The consumption of hot or spicy foods is generally associated with increased blood circulation and vasodilation, and this may be partly owing to increased NO production, amongst other factors. Hot components of foods are discussed with relation to potential imbalances they can cause on the Digestive Disorders page. All of the above vanilloids mentioned above that are found in food sources, e.g. Vanilla, Capiscum etc. are hot in nature.
Natural vanilla does have some health benefits that should be mentioned in this context, including antioxidant properties, anti-cancer properties, as an aid to preventing the sickling in red blood cells in Sickle Cell Disease as well as a treatment for stomach ulcers and insomnia (sedative properties).
If over-stimulation of Vanilloid Receptors is indeed a problem in your case (as well as excessive NO/ONOO- in general), unless you are eating large quantities of Vanilla flavoured products every day, it should not be an issue. Elevated Adrenaline and Noradrenaline levels may well be more of an issue. Consumption of black pepper and other spicy food may be ill advised.
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Hyper-Excitment of Muscarnic Acetylcholine Receptors:
Muscarinic receptors (mAChRs) are G protein-coupled Acetylcholine (ACh) receptors found on the outer plasma membranes of certain neurons and other cells. One of their roles is acting as the main end-receptor stimulated by the neurotransmitter ACh released from postganglionic fibres in the parasympathetic nervous system. Their name derives from their sensitivity to muscarine compared with nicotene (which is not a biological function of the receptors in the body). Their counterparts are nicotinic Acetylcholine receptors (nAChRs). Both these classes of receptor are thus stimulated by ACh.
http://en.wikipedia.org/wiki/Muscarinic
There are 5 types of mAChR receptors, M1 to M5. M1, M3 and M5 (M-odd receptors) are quite similar and when stimulated, produce increased levels of cytoplasmic Calcium ions (Ca2+) in the cell. M-odd receptors differ from NMDA and Vanilloid receptors in that they release their Ca2+ by a different pathway. They trigger synthesis of the chemical messenger IP3 (Inositol Triphosphate - a Phytate), which releases intracellular Ca2+ from certain Ca2+ stores that are sequestered away in the cell (rather than simply allowing outside Ca2+ into the cell as the other receptors discussed above do). The increased intracellular Ca2+ concentration will lead to increased NO production by nNOS and eNOS (the two Ca2+ dependent NOSes).
Pall suggests that excessive ACh levels and over-stimulation of the Muscarinic receptors on account of exposure to pesticide organophosphate or carbamate pesticides and/or organic solvent toxicity are triggers found in some MCS and CFS cases. In insects and invertebrates, these pesticides kill by inhibiting the enzyme Acetylcholinesterase, theenzyme that breaks down Acetylcholine. This allows ACh levels to build up, thus causing toxicity through excessive Muscarinic receptor activity. This releases more NO, thus feeding the NO/ONOO- cycle. A similar pattern is expected in human cases of exposure to such chemicals.
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Low Tissue Oxygenation and Capillary Budding:
Low levels of tissue oxygenation is likely to be a significant factor in many CFS cases. When the target cells at the capillaries are not receiving enough oxygen over a period of time, perhaps because of clogged up capillaries, high levels of oxidised hemoglobin (methemoglobin) or low 2,3-BPG levels, they will start to release a chemical called Vascular Endothelial Growth Factor (VEGF). This is a chemical signal to produce more capillaries in that area, or capillary budding as it is sometimes referred to. The idea is to produce more capillaries locally which should hopefully increase blood supply to those affected cells. The endothelial linings of these newly created 'budded' capillaries produce extra nitric oxide (NO), in order to induce vasodilation and increase blood supply to these target cells. If the extent of capillary budding is significant, then there may be significantly elevated levels of NO in the body.
Hypoxia can also result in increased Superoxide production, which may react with the additional NO being produced in similar conditions and produce more Peroxynitrite.
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Toxicity:
Pall has suggested that exposure to the following toxic compounds (cumulative effect over long term, low level exposure (or one or more) or a single high-level exposure incident - or consecutive incidents) are implicated in the initiation of the illnesses of CFS, ME, Multiple Chemical Sensitivies, Fibromyalgia by stimulating the Nitric Oxide/Peroxynitrite cycle:
- Organophosphorus Pesticides - CFS, ME, MCS - one of most common causative factors
- Carmbamate Pesticides - MCS
- Organochlorine Pesticides - MCS
- Pyrethroid Insecticides (Commercial and Domestic) - MCS
- Volatile Organic Solvent Exposure - MCS - one of most common causative factors
- Mercury - MCS
- Ciguatoxin (a type of poison found in reef fishes whose flesh is exposed to toxins produced by dinoflagellates (a type of plankton)) - CFS, ME
- Carbon Monoxide - CFS, ME, MCS
- Hydrogen Sulphide - MCS
http://thetenthparadigm.org/mcs09.htm
Heavy metal toxicity is most likely responsible for excessive immune system iNOS induction. Heavy metal toxicity, as well as impairing a number of processes in the body, also instigates an enormous increase in free radical formation. This oxidative stress on the body is a problem in of itself but it also triggers an inflammatory response from the body, partly in the form of iNOS induction, producing more Nitric Oxide.
Please note that heavy metal toxicity as a trigger does not just apply to cumulative toxicity through exposure, but can also apply to excessive or inappropriate chelation therapy for the removal of heavy metals. Excessively aggressive chelation, especially the use of mobilising agents, may increase levels of circulating heavy metals in the bloodstream, triggering more free radical production. Some symptoms of excessive detoxification including liver spots, which are swellings or boils (i.e. the body's inflammatory immune response to excessive liberated toxins). This may spiral out of control if the level of inflammation is already elevated or if sufficient breaks are not taken. If you are in the middle of a chelation programme and are suffering worse symptoms of inflammation, it is probably wise to take a break and focus more on antioxidant therapy until symptoms subside, as otherwise you may make it worse.
Of course, individual cases may well have more than one stressor and not necessarily as classified above. These comorbid conditions are fluid and vary in their progression and exact nature according to the individual.
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Psychological Stress or Trauma:
According to Pall, excessive psychological stress over one's childhood or recent adulthood, or a single psycholgically traumatic incident is thought to significantly raise NO production and levels in the body. This is noted as the key driver in most Post Traumatic Stress Disorder (PTSD) cases and may play some role in CFS, ME and Fibromyalgia patients.
Inducible NO synthase (iNOS) is upregulated in lungs and liver during shock and plays a role for the generation of large amounts of NO during shock or following stimulation of tissues with a variety of proinflammatory mediators.
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Physical Trauma:
According to Pall, physical trauma is sometimes implicated in the onset of PTSD, CFS, ME and Fibromyalgia cases. Head and neck trauma is particularly relevant in Fibromyalgia cases, and head trauma oftenrelevant in PTDS cases.
Inducible NO synthase (iNOS) is upregulated in lungs and liver during shock and plays a role for the generation of large amounts of NO during shock or following stimulation of tissues with a variety of proinflammatory mediators.
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Ionising Radiation Exposure:
According to Pall, ionising radiation exposure is implicated in the onset of CFS and ME in some patients, perhaps a cumulative effect of repeated exposures. Ionising radiation may come from a variety of sources, other than just medical or dental.
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Pre-Existing Autoimmune Disease or Inflammatory Condition:
Whilst this is probably a chicken and egg situation, it is worth mentioning. Any type of inflammatory or autoimmune disease or condition will be characterised by increased levels of free radicals, including Nitric Oxide and Peroxynitrite. Such a condition in many cases may result in other parallel conditions arising, that are also fed by the Nitric Oxide/Peroxynitrite pathway. This is why such conditions are often referred to as being comorbid. CFS may arise from MCS, Fibromyalgia may arise from CFS or the other way around, over time. CFS may arise from Multiple Sclerosis or IBS. Pall notes that this is particularly relevant for Fibromyalgia, which may sometimes arise out of a pre-existing autoimmune disease.
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Genetic Predisposition to Elevated Nitric Oxide Production:
Two genes have been identified in 5 studies as being implicated in CFS development, implicated in increased Nitric Oxide production. These are:
- CBG gene
Defective CBG proteins have been associated with CFS cases, whereby the defective function of the CBG protein affects its ability to transport cortisol, predisposing such individuals to potentially developing CFS, along with many other possible acquired factors. Cortisol has a key role in lowering the induction of iNOS (immune system NO production enzyme), and lowered cortisol levels may be associated with elevated NO levels.
- Angiotensin converting enzyme (ACE) gene
A polymorphism of this ACE gene has been associated with CFS and GWS in studies. Angiotensin II, the protein produced by the ACE protein, acts to elevate Superoxide levels.
In addition, another study from Rowe's Laboratory links orthostatic intolerance and CFS to Ehlers-Danlos Syndrome:
- Ehlers-Danlos syndrome
Ehlers-Danlos syndrome is a collection of diseases characterised by mutation in a subunit of the protein collagen or an enzyme that modifies the structure of collagen. Collagen is main structural protein in the body. Ehlers-Danlos mutations can affect vasculature, resulting in less effective perfusion (blood supply of O2 and nutrients into the tissues) of the elevated tissues of the body and resulting tissue hypoxia in these elevated tissues. Hypoxia can lead to Peroxynitrite production (i.e. through increased NO and O2- production). This may explain why some CFS patients prefer to lie down and remain in bed. However, it can work both ways, as blood perfusion and diffusion of O2 and CO2 may be impaired in the supine posture and may be improved in an upright posture, depending on brainstem function.
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Too Low Nitric Oxide Levels? David Whitlock's Hypothesis:
'An Engineering Perspective on CFS' (7 Nov. 2008) - by Dave Whitlock
In the above article (discussed by BlackSpy on the Mitochondrial page), Dave Whitlock argues that low basal NO levels may explain low levels of mitochondrial regeneration, resulting in lower numbers of mitochondria per cell than a normal, healthy person. NO (Nitric Oxide) is a major regulator of ATP levels. Low NO levels causes low ATP levels, which thus disables autophagy, preventing recycling of mitochondria. There is more peroxynitrite damage observed not because peroxynitrite levels are high and NO levels are higher, but because there is less recycling of mitochondria occuring (less autophagy) and hence less repair of peoxynitrite-damaged proteins and lipids. In other words, there is a resulting accumulation of peroxynitrite-damaged proteins. Because of low NO levels, there is less synchronisation between cells in terms of their energy output (in a muscle group or particular organ), meaning some are overloaded and some are underloaded. According to Whitlock, techniques do not exist to measure if adjacent cells are working 'in sync'. Whitlock proposes a number of methods of boosting NO levels (or more specifically NO donors) in the body to allow the body to produce more mitochondria, which include (in no particular order and not necessarily recommended by BlackSpy as this is a THEORY) taking Nitroglycerine, L-arginine, Viagra, eating more green leafy vegetables, and meditation.
Paul Cheney and Martin Pall argue the exact opposite, that NO levels and Peroxynitrite levels in CFS patients tend to be higher than normal, rather than lower, on account of the enzymatic activities associated with over-immune system activation, on account of prolonged exposure to viri or bacterial infections etc., amongst other factors. Cheney proposes a number of methods of reducing one's NO production. As to who is correct, BlackSpy is not certain, and it presumably depends on the exact individual in question as to what is going on on a specific biochemical level and where. Everyone however is probably in agreement that poor mitochondrial function is behind cardiac insufficiency.
Supplements are available that are designed to stimulate eNOS production, to improve vascular function in afflicated individuals (who do not produce sufficient enthelial NO). This can help to prevent atherosclerosis on account of arterial wall thickening, and also improve oxygen and nutrient delivery. NO stimulating supplements are also taken by weight lifters to improve performance. Clearly those who are producing too much NO should not consider such a regime as it will exacerbate their symptoms. One example of such a supplement is Xymogen's N.O.max ER, which contains Arginine alpha-ketoglutarate and ACTINOS2 Whey Peptide Fraction, but shown to stimulate Endothelial NO production. Such a supplement could probably be used for those travelling at high altitudes or with erectile problems (if NO is really the main cause).
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Superoxide:
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Introduction:
Superoxide is a relative unreactive free radical (Gerdes, 2003). Superoxide can also act as a intracellular messenger molecule, like NO.
There are two main types of Superoxide. The predominant form of Superoxide is OO- or O2-, where there is an unpaired electron (characteristic of free radicals). Superoxide does not generally move very far from its point of creation within the cell and cannot easily pass through cellular membranes on account of its negative electrical charge. The alternate form is its acidic form, where it binds with a Hydrogen (H+) ion (from an acid) to form HOO. HOO has no negative charge and is more easily able to pass through cell membranes. However, it is only makes up 0.1% of the body's total Superoxide.
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Formation of Superoxide:
There are 5 main pathways to the creation of Superoxide. These are listed in descending order (by Pall) of the amount of Superoxide the relative pathways produce on average:
- Electron transport chain inside mitochondira - O2- is one of the intermediate byproducts of respiration and energy production. O2- levels may become elevated by the presence of Peroxynitrite (see below). Superoxide formation as an intermediate free radical during respiration is discussed on the Oxidative Stress page.
- Uncoupled nitric oxide synthases (NOS) - production of O2- by NOS occurs when levels of L-Arginine and/or BH4 are low and it is not possible to synthesise NO in sufficient quantities (as described above). Peroxynitrite oxidation of BH4 may be partly responsible for this increase in O2- production in place of NO production.
- Xanthine Oxidase activity- Hypoxia (low O2 stress) increases the conversion of the Xanthine dehydrogenase enzyme to Xanthine Oxidase because of the effect of hypoxia on intracellular Ca2+ levels and energy metabolism. Xanthine oxidase generates O2- when it oxidises compounds such as hypoxanthine. Xanthine oxidase acivity may also be increased when cells are depleted of reduced GSH (Glutathione) (e.g. when cells are under oxidative stress). This may result in yet further O2- production. An increase in Xanthine Oxidase levels may thus result in increased O2- production. Hypoxia can also result in increased NO production from capillary budding - please see the NO section above. These two factors may result in elevated Peroxynitrite formation.
- NADPH oxidase enzyme activity in Phagocytes (White Blood Cells) - Phagocytes consume O2 and use it to generate O2-, which is used by the NADPH oxidaze enzyme to generate a variety of different oxidants that are used to kill the fungi and bacteria that they ingest. This can be a substantial source of O2- and other oxidants in infected tissues. An increase in O2- production may thus result from the immune system's inflammatory response.
- Cytochrome P450 enzymes - the decoupling reaction of the P450 catalytic cycle (addition of O2 to the Iron in the Heme group of the P450) results in the release of an O2- radical. However it is not thought that this is a significant factor in the NO/Peroxynitrite cycle.
In the following 2007 paper, Alvarez et al. identify NADPH oxidase enzyme activity as being the main source of Superoxide, the vasoconstrictor, (the inflammatory response from Phagocytes), which reduces the amount of NO available from increased iNOS activity than there would otherwise be, to form Peroxynitrite.
'Role of NADPH oxidase and iNOS in vasoconstrictor responses of vessels from hypertensive and normotensive rats'. Alvarez et al. 2007.
www.ncbi.nlm.nih.gov/pmc/articles/PMC2267276/
'Hypertension is associated with elevated levels of circulating proinflammatory cytokines, which may alter the vascular expression of enzymes like inducible nitric oxide synthase (iNOS) and modify the regulation of vascular tone during this pathology. Indeed, increased vascular iNOS activity and/or protein expression have been described in hypertension. The role of iNOS-derived NO in vasoconstrictor and endothelium-dependent vasodilator responses has been previously analysed by our group and others in lipopolysaccharide or interleukin-1-beta-stimulated arteries. However, the participation of iNOS-derived NO in vasoconstrictor responses in unstimulated vessels is not well studied.
Oxidative stress can affect vascular reactivity by different mechanisms. Reactive oxygen species function as second messengers, activating numerous signalling molecules and play an important role in vascular physiopathology. Several sources of superoxide anion (O2-) within vessels have been described. Among them, xanthine oxidase, uncoupled NOS and COX can produce O2- in different conditions. However, at the vascular level it is well established that nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) oxidase, present in all three vessel layers, is the main source of O2-. An increase of O2- production has been observed in human and different experimental models of hypertension, including spontaneously hypertensive rats (SHR). More specifically, the enhanced O2- generation in hypertension is a known result of the activation of vascular NAD(P)H oxidase.
The mechanisms whereby increased O2- production might contribute to high blood pressure are currently under active investigation. However, it is also well known that by interacting with NO, O2- forms peroxynitrite, thus decreasing NO availability for smooth muscle relaxation. Hypertension is associated with changes in vascular responses, such as impairment of endothelium-dependent vasodilator responses or enhancement of vasoconstrictor response to different agonists. Several studies have analysed the relationship between increased O2- production and the impairment of endothelium-dependent relaxation in hypertension. However, the O2- contribution to the altered vasoconstrictor responses in hypertension as well as its relationship with the iNOS-derived NO is less studied. The present study was performed to analyse how hypertension might alter the role of O2- in the vasoconstrictor responses to phenylephrine, the sources of this O2- and its relationship with iNOS-derived NO.'
Hypertension is associated with increased activity and/or expression of iNOS as well as increased production of O2- in different vascular beds; these changes might contribute to the alterations in vascular tone occurring in this pathology. The main results of the present study suggest that the increased production of O2- derived from NAD(P)H oxidase, observed in aorta from hypertensive rats, counteracts the enhanced production of NO derived from iNOS, occurring in hypertension, and the modulation exerted by NO of vasoconstrictor responses.'
'...hypertension increases iNOS expression but decreases the bioavailability and the modulation elicited by iNOS-derived NO of contractile responses in aorta as a result of the increased O2¥? production from NAD(P)H oxidase.'
Increased Superoxide formation tends to result in increased formation of the rogue oxidant molecule Peroxynitrite (which degrades into various Reactive Nitrogen Species (RNS)). Peroxynitrite is a vasoconstrictor, in a similar way to Superoxide and is implicated in cases of Hypertension.
'Peroxynitrite versus nitric oxide in early diabetes'. Robert D.ÊHoeldtke et al. 2003.
www.nature.com/ajh/journal/v16/n9/abs/ajh2003141a.html
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Genetic Predisposition to Elevated Superoxide Production:
- Serotonin transporter gene
Certain forms of the Serotonin transporter gene may result in increased transport and consequently lower extracellular Serotonin levels, and are associated with CFS cases. This may lead to decreased HPA axis function, which in turn, may lead to lowered Cortisol secretion.
- Ehlers-Danlos syndrome
As discussed above in the section above on Genetic Predisposition to NO Production, a study from Rowe's Laboratory links orthostatic intolerance and CFS to Ehlers-Danlos Syndrome. Ehlers-Danlos syndrome is a collection of diseases characterised by mutation in a subunit of the protein collagen or an enzyme that modifies the structure of collagen. Collagen is main structural protein in the body. Ehlers-Danlos mutations can affect vasculature, resulting in less effective perfusion (blood supply of O2 and nutrients into the tissues) of the elevated tissues of the body and resulting tissue hypoxia in these elevated tissues. Hypoxia can lead to Peroxynitrite production (i.e. through increased NO and O2- production). This may explain why some CFS patients prefer to lie down and remain in bed. However, it can work both ways, as blood perfusion and diffusion of O2 and CO2 may be impaired in the supine posture and may be improved in an upright posture, depending on brainstem function.
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Superoxide Dismutase:
The majority of Superoxide is produced during respiration, inside the mitochondria, but there are mechanisms in place to lower its levels on account of it being sufficiently damaging to cellular structures.
The endogenous antioxidant enzyme that is responsible for neutralising Superoxide free radicals are known as Superoxide Dismutase (SOD). There are 3 main types of Superoxide Dismutase enyzymes, each found in a specific location. Each type of SOD is encoded by its own gene and each has a distinct structure.
- Mitochondrion - intracellular - inside the mitochondrial membrane, to protect the inner mitochondrial membrane from free radical damage from O2- produced during energy production and respiration.
- Cytoplasm -intracellular - protects the inside of the cell (but outside of the mitochondria) from Superoxide damage
- Secretory - extracellular - this type of SOD is secreted on the outside of cells and serves to neutralise SOD in extracellular spaces in the body.
The SOD antioxidant enzyme is effectively oxidised by Superoxide, which reduces the Superoxide. The SOD can then be recycled by reduction so it can be used again to neutralise the next Superoxide free radical. However, if any Superoxide reacts with NO to form Peroxynitrite, this Peroxynitrite can actually destroy the SOD enzyme. Excessive destruction of SOD means fewer protective antioxidant enzymes to keep O2- at bay, so more O2- builds up. In the presence of elevated NO levels, yet further Peroxynitrite can be produced. Mitochondrial damage caused by excessive Superoxide levels in one mechanism of many in some CFS cases.
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Peroxynitrite (ONOO-):
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Introduction:

The Peroxynitrite anion is shown above. Peroxynitrite is an unstable 'valence isomer' of the nitrate ion, NO3-. It is mostly commonly written as 'ONOO-' but can also be expressed as 'ONO2-'.It is a powerful oxidant/oxidising agent (not actually a free radical) and nitrating agent. It is also a vasocontrictor (see Superoxide section above for details).
http://en.wikipedia.org/wiki/Peroxynitrite
Most of the harmful effects of Peroxynitrite are produced not by the ONOO- itself but by its breakdown products.
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Formation of Peroxynitrite:
Peroxynitrite is formed by the reaction of two free radicals, Nitric Oxide with Superoxide.
O2- + NO. -> ONO2-
The two free radicals combine so readily on account of the presence of an unpaired electon on the outer shell of each. The resulting molecule, Peroxynitrite, is not a free radical but a powerful oxidant. The reaction is said to be diffusion limited. In other words, every time a molecule of O2- collides with an NO molecule, the react to form ONOO-.
Superoxide is an oxidising free radical, as is Nitric Oxide, but Peroxynitrite is more powerful an oxidant than the sum of its constituent parts.
Dr Paul Cheney, as stated in some of his seminars, believes that Peroxynitrite is primarily formed by Superoxide (a byproduct of ADP to ATP conversion, i.e. energy production, inside each cell) leaking out of the mitochondria and reacting with Nitric Oxide (NO - a byproduct of NOS enzyme activity). This is not strictly speaking correct. Some ONOO- is indeed formed inside the mitochondrial membranes, but normally only a very small amount. The Superoxide Dismutase (SOD) present in the mitochondria inhibits ONOO- production by reacting with the O2- before it can react with NO to form ONOO-. The mitochondria also contain some levels of Glutathione (hopefully sufficient) to protect the mitochondrial membranes against ONOO-. As discussed above, Superoxide is produced outside of the mitochondria as well inside them, so the Superoxide that reacts with NO to form ONOO- in the cytoplasm of cells and also outside of the cells themselves is far more likely to be responsible for cystoplasmic and extracellular ONOO- than Superoxide 'leaking' out of the mitochondria.
The Superoxide produced as part of respiration and ADP to ATP conversion stays inside the inner mitochondrial membrane. It can only escape and 'leak out' if the mitochondrial membrane is damaged. This can and does of course occur, especially in some CFS patients with excessive free radical damage, but not to the extent that would be necessary to account for such Peroxynitrite build up in the body. Indeed, this degree of mitochondrial membrane damage would likely result in death, as demonstrated by laboratory mice that had no mitochondrial SOD and had their mitochondrial membranes attacked and ravaged by O2-, which did not live very long. In the majority of CFS cases, this route is unlikely to be the dominant one for ONOO- production in the body. The mechanisms cited by Martin Pall above seems to make more sense, including the production of SOD by cytoplasmic NOS enzymes (outside the mitochondria) in the absence of sufficient L-Arginine or BH4 to make their usual NO.
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Other Reactive Nitrogen Species (RNS) Formed from Peroxynitrite:
http://en.wikipedia.org/wiki/Reactive_nitrogen_species
Reactive Nitrogen Species (RNS) are a family of antimicrobial molecules and free radical species derived from NO. RNS react together with Reactive Oxygen Species (ROS) (e.g. Superoxide) to damage cells, causing nitrosative stress. RNS and ROS are collectively referred to as ROS/RNS. ONOO- is a highly reactive oxidising and nitrating agent and tends to react with other molecules to produce additional types of RNS free radicals and oxides of Nitrogen (e.g. NO2). NO2 is a good oxidiser also, and which can also react with NO to produce N2O3, another powerful oxidiser. Examples are listed below.
- Nitrosperoxycarbonate (ONOOCO2-) / Radical Carbonate (CO3-)
ONOO- readily reacts nucleophilically with CO2, donating both of its bonded or shared electrons to form Nitrosoperoxycarbonate (ONOOCO2-). CO2 is of course produced by respiration as discussed on the Tissue Oxygenation and CFS page. CO2 is mainly in the form of Bicarbonate (HCO3-) in the blood and tissues, with a small amount dissolved as CO2 and also bonded to Hemoglobin.
ONOO- + CO2 -> ONOOCO2
Most of the ONOO- formed in the body from NO and O2-, does not remain as Peroxynitrite, but immediately reacts with the ubiquitous CO2 in the body, which is the predominant pathway for ONOO-. In other words, most of the free radical damage caused by Peroxynitrite is actually caused by the downstream products of Peroxynitrite, chiefly those formed from Nitrosperoxycarbonate (i.e. the Carbonate Radical CO3- discussed below), rather than the actual direction oxidation by ONOO- itself on the body's lipids and protein structures. However, for simplicity's sake, most commentators simply refer to 'Peroxynitrite' when they mean the actual downstream reacted products of Peroxynitrite.
Nitrosperoxycarbonate (ONOOCO2-) homolyzes (dissassociates) to form a Carbonate free radical (CO3-) and Nitrogen Dioxide (NO2).
onooco2- -> CO3- + NO2
CO3- is the radical form of Carbonate which has the chemical formula CO3-- or CO3(2-). In other words the Carbonate Radical has on less electron (i.e. it has one unpaired outer electron), making it hugely more reactive and a free radical. Both the Carbonate Radical and Nitrogen Dioxide Radical are responsible for the majority of the Peroxynitrite-related oxidative stress and damage in the body. The Carbonate Radical however could be considered the more reactive and nastier of the two.
- Peroxynitrous Acid (HOONO) /Hydroxyl Radical (OH-)
According to Pall, Peroxynitrous acid, the acidic form of Peroxynitrite (HOONO) is present in the cell in approximately 1:3 of Peroxynitrous acid to Peroxynitrite (which has not reacted with CO2). It is formed when the Peroxynitrite ONOO- anion is in the presence of an acid (i.e. the H+ cation), the two bonding to form Peroxynitrous acid. It is relatively unstable. It can be written (expressed) as HOONO or ONOOH.
http://en.wikipedia.org/wiki/Peroxynitrous_acid
Perxoynitrous acid (HOONO) breaks down or homolyzes to form caged radical Nitrogen Dioxide (NO2) and the Hydroxyl (Free) Radical (OH). Both of these radicals can react to cause damage to important molecular structures in the body.
ONOO- + H+ -> HOONO -> NO2. + OH.
Approximately 2/3rds of the NO2 and OH radicals produced from HOONO exchange an electron (i.e. electron transfer) to produce the unstable NItronium cation (NO2+) and Hydroxide anion (OH-).
HOONO -> OH- + NO2+
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Pathological (Detrimental) Pathways of Peroxynitrite:
Excessive peroxynitrite formation is postulated in the 2004 Paul Cheney interview document (see the Cardiac Insufficiency page for more information) as the primary force behind free radical damage and impaired mitochondrial function.
Peroxynitrite (free radical) formation is partly behind the development of Cancer and also Coronary Artery Disease. Cheney believes this is the main driver behind CICM and CFS.
- Inactivation of Iron-Sulphur Proteins:
ONOO- and its related products (including NO) can inactivate iron-sulphur proteins. The most important of which arguably are those found in certain Mitochondrial enzymes that are part of the Krebs Cycle (Citric Acid Cycle), e.g. Aconitase enzyme. The damage to these enzymes (proteins) is irreversible and the only way their functionality can be restored is through resynthesis of these proteins. Damage to these proteins may result in a bottleneck in the Krebs Cycle and accumulations of both cis-aconitate and its precursor citrate. Succinate dehydrogenase (a.k.a. Succinate-coenyme Q reductase (SQR) or Complex II) is another example, and it participates in both the citric acid cycle and the electron transport chain.
- DNA Damage:
Several types of DNA damage can be inflicted including the nicking of of the backbone of DNA chains. These nicks stimulate the poly (ADP-ribose) polymerase enzyem, which uses Active Vitamin B3 (NAD) as a substrate. NADH is the reduced form of Active B3 that is involved in the electron transport chain in mitochondria. Therefore elevatd poly (ADP-ribose) polymerase enzyme production on account of the DNA damage caused by ONOO- can lead to a depletion of the pools of NADH/NAD that are normally used in mitochondrial function, thus heavily impacting ATP availability and energy levels. NADH supplementation may therefore be beneficial to overcome this deficit in the mitochondria. NADH does stimulate NO production, but if its levels are very low in the mitochondria, then is not likely an issue until levels greatly exceed requirements (rather difficult but possible).
- Oxidative Chains Reactions, Including Lipid Peroxidation:
ONOO- and its products can instigate lipid peroxidation, i.e. oxidation of the lipids in biological and cellular membranes, in particular, mitochondrial membranes. Cell membranes are made up Essential Fatty Acids and Phosphatidyl Choline on the whole, both of which are polyunsaturated, and can be easily oxidised. Lipid peroxidation causes many changes in cellular functioning, and lipid peroxidation of the mitochondrial membranes can affect mitochondrial functioning. The latter is more likely to be caused by Superoxide than ONOO-, although ONOO- can still be significant.
- SOD Destruction:
The Superoxide Dismutase (SOD) protective enzyme as described above is a protective antioxidant enzyme used to neutralise Superoxide. The SOD antioxidant enzyme is effectively oxidised by Superoxide, which reduces the Superoxide. The SOD can then be recycled by reduction so it can be used again to neutralise the next Superoxide free radical. However, if any Superoxide reacts with NO to form Peroxynitrite, this Peroxynitrite can actually destroy the SOD enzyme. Excessive destruction of SOD means fewer protective antioxidant enzymes to keep O2- at bay, so more O2- builds up. In the presence of elevated NO levels, yet further Peroxynitrite can be produced. Mitochondrial damage caused by excessive Superoxide levels in one mechanism of many in some CFS cases.
- Nitration and Oxidation of Proteins:
Modification of proteins by oxidation and nitration to form products such as Protein Carbonyls and 3-Nitrotyrosines
- Stimulation of NF-kB DNA transcription factor:
The oxidant products of ONOO-, as well as other oxidants and free radicals, stimulate the activity of