The author of this blog contacted me to write a short piece on how I understand the role of NO in CFS and my suggestions on how to deal with it. I am not a clinician, I am a researcher in NO (nitric oxide) with a chemical engineering background, so I tend to see physiology as a complicated chemical plant with exquisitely complex, precise, distributed and redundant control systems. We are mostly ignorant of the details of that control system, but that there is a control system and that it (usually) functions exquisitely well is beyond doubt. In CFS, much of that disruption results from low basal nitric oxide (my hypothesis).

I have a financial interest in the use of topical ammonia oxidizing bacteria to treat CFS and other things, but that is not yet ready to be available to the public. When the nitric oxide bacteria are available there will be a notice on that site. I have a blog where I discuss my research in NO and how low NO fits into many of the disorders of modern civilization.

CFS is a chronic condition. In the absence of irreparable damage, all chronic conditions can only result from a chronic disruption of the control system(s) that regulate that system. The only satisfactory resolution of a chronic condition can be by a restoration of the normal function of the control system regulating that system, which in the absence of irreversible damage should restore normal function.

The major symptom of CFS is exercise intolerance; that is fatigue brought upon by modest muscle activity. Muscle strength is not greatly decreased, but endurance is. Muscle is aerobic tissue, and to maintain metabolic output must generate ATP via oxidation which only occurs in mitochondria. CFS occurs due to an insufficient ATP production rate by the mitochondria in muscle. An insufficient ATP production rate in muscle comes from not enough mitochondria in those muscles. Chronic not enough mitochondria can only come from a chronic disruption of the regulation of mitochondria turnover and mitochondria biogenesis.

Mitochondria have their own genome, which codes for 13 proteins and those proteins are synthesized inside mitochondria. The other 1000-2000 proteins in mitochondria are coded for by nuclear DNA, synthesized in the cytoplasm and ported into mitochondria during mitochondria biogenesis. Mitochondria have a limited lifetime; they wear out and are replaced. In rat heart muscle the half life is about 18 days. I haven’t found specific references to lifetime in skeletal muscle; it is probably longer, but probably not many times longer. If half the mitochondria are replaced in 18 days, that implies replacement of ~6% per day.

Mitochondria are recycled by the process of autophagy, where cytoplasm and organelles inside cells are engulfed in a vacuole, proteases ported in, the contents broken down, and the broken down bits recycled. That recycling process consumes ATP, so it is not something that physiology wants to do if there isn’t enough ATP available. I think that is the fundamental problem of CFS. If there isn’t enough ATP, the cell puts off recycling mitochondria until later, but if later never comes the cell is left with old, tired and dysfunctional mitochondria and not fresh new vigorous ones. Usually this mitochondria turnover and replacement occurs at night, during sleep, during periods of minimum ATP demand.

It turns out that NO is a major regulator of ATP level via the common action of ATP and NO on guanylyl cyclase (sGC). Low NO causes low ATP levels which turns off autophagy and which prevents recycling of mitochondria. Mitochondria biogenesis is also triggered by NO through sGC.

Few mitochondria can produce more ATP, but they make more superoxide when they do so. Physiology has an unlimited capacity to produce superoxide, limited only by the supply of O2 and reducing equivalents. A state of stress is a low NO state. In the short term this is good because the superoxide lowers the NO level which disinhibits cytochrome c oxidase and allows mitochondria to consume more O2 and to lower O2 levels so more O2 can diffuse to the site of consumption. This low NO also lowers the ATP level which turns off pathways not needed during periods of high ATP demand such as autophagy and other aspects of healing. In the short term this is good because the ATP not consumed by autophagy might let you take a few more steps and escape from the bear chasing you. In the long term it results in not enough mitochondria and chronic fatigue.

My hypothesis is that this state of not enough mitochondria occurs (usually) because of immune system stimulation under conditions of high stress (such as vaccinations while in a war zone) and for that state of high stress and immune system stimulation to occur for a time which is long compared to the mitochondrial turnover time. Physiology remodels to accommodate the high stress state and causes CFS. Other things can do it too, any hypermetabolic state as from trauma, especially in conjunction with immune system stimulation. This results in a chronic state of fewer mitochondria producing the same basal ATP production rate (so “at rest” there is enough ATP), but there are no excess mitochondria so there is essentially no reserve capacity to produce ATP at a higher rate during even modest exertion. When the ATP equivalents stored as phosphocreatine are consumed, the mitochondria can’t keep up with demand so fatigue occurs. Exercise per se doesn’t increase endurance; the increased endurance following exercise is due to the pruning of dysfunctional mitochondria during exercise (which causes fatigue) and their replacement with more and better functioning new mitochondria. This replacement occurs during periods of rest following exercise, not during the exercise itself. Exercise produces signals that trigger the production of increased numbers of mitochondria. My research suggests that some of those signals result from nitrated proteins in the recycled mitochondria.

Sleep is a period of high NO level. When nitric oxide synthase is inhibited, so is sleep. Disruption of sleep is another major symptom of CFS. Sweating during sleep is another. It is my hypothesis that sweating during sleep occurs to provide ammonia to the bacteria I am working with so that they generate NO/NOx on the skin, some of which is absorbed and that this is an important aspect of normal regulation of NO/NOx physiology.

Superoxide and NO and their reaction product peroxynitrite are essential signaling molecules. They are used to switch physiology from a state dominated by NO (the normal at rest state) to a state dominated by superoxide (the high stress “fight or flight” state). Repair consumes ATP. When there isn’t enough ATP (as when running from a bear), it is better to turn off repair and escape then to keep repair on and be caught. This is what physiology does, which is why chronic stress slows healing.

A low ATP state and a low NO state occur simultaneously. NO is the diffusible signal that signals the ATP status between cells so that an entire tissue compartment or organ can be regulated “in sync”. The cells have to be regulated “in sync” because if they were not, external control of what ever that tissue compartment is providing (force (muscle), glucose (liver), insulin (pancreas), urine production (kidney)) becomes unstable and the metabolic load is not divided among the cells. Some cells become overloaded while some cells are underloaded. This causes inefficiency and in extreme cases damage as the overloaded cells go into emergency overload. I suspect that this is part of many of the degenerative diseases, the metabolic load in an organ isn’t shared equally among the cells. We don’t have techniques to measure if adjacent cells are working “in sync” or not.

Peroxynitrite occurs during the transition between a state dominated by NO and the state dominated by superoxide. The superoxide dominated state (characterized by oxidative stress) is easy to enter, and is one of the fundamental stress responses that organisms evolved long ago. There are many pathways to accomplish that on many different time scales (some of them are extremely fast; if a bear crashed through the wall your body would invoke the “fight or flight” state in a heart beat). Escape from a predator is a life-or-death situation that our ancestors had to respond to even when they were still single celled organisms. Successful escape requires mobilizing sufficient ATP and converting that into motion sufficient to flee. ATP production rate is limited; the optimum organism will efficiently allocate ATP over time, which means turning off long term needs when there are higher priority short term needs. Anything that takes longer than the escape can be turned off because what ever it is doing can’t affect the outcome other than by making it worse by consuming ATP that could otherwise be used for escape.

Martin Pall has presented a hypothesis that CFS results from peroxynitrite damage to mitochondria and other components of cells, and that this peroxynitrite damage is due to too much NO. This is incorrect. Peroxynitrite is a normal and absolutely necessary signaling molecule. Peroxynitrite only occurs in vitro when near equimolar fluxes of superoxide and NO are produced. When there is an excess of either NO or superoxide then peroxynitrite and damage due to peroxynitrite is not observed. In CFS it is observed that there is an increased accumulation of peroxynitrite damaged proteins. At steady state, production minus repair equal accumulation. The accumulation of damaged proteins can occur either from an increased rate of production (at constant repair) (Pall’s hypothesis) or from reduced repair (at constant or even reduced production rate) (my hypothesis).

Because peroxynitrite is a normal signaling molecule, peroxynitrite “damage” occurs all the time. Peroxynitrite “damage” is not observed in normal individuals because the damage is repaired essentially as quickly as it occurs so there is no accumulation. It is not strictly correct to call it “damage”. Peroxynitrite is one of the necessary regulators of mitochondria, and it does turn off some mitochondrial enzymes. This is not “damage”, it is an absolutely necessary and normal regulatory function. Mitochondria have a finite lifetime that is short compared to the lifetime of the organism. When mitochondria reach the end of their lifetime they need to be disposed of properly because mitochondria have enormous capacity to consume O2, substrate and to generate superoxide and hydrogen peroxide. A few percent “bad” mitochondria producing superoxide at their limit would kill the cell they are in. This doesn’t happen because physiology turns off those mitochondria before it can happen. That is one of the roles of peroxynitrite. I have a whole blog on mitochondria damage.

Because the body has unlimited capacity to produce superoxide, the transition from a NO dominated state to a superoxide dominated state is always fast. It is only during the transition that peroxynitrite is created and can cause “damage”. The transition from the superoxide dominated state to the NO dominated state is much more difficult. There are many things that trigger the “fight or flight” state, all of them have to be “off” for physiology to give the “all clear” signal and for physiology to stand down from the fight or flight state.

Switching from the superoxide dominated state to the NO dominated state requires enough NO to overcome the hysteresis of the “fight or flight” state. With enough NO, the transition can be rapid and sharp, with minimal lingering in the state where there are near equivalent amounts of NO and superoxide (which is where peroxynitrite and peroxynitrite damage occur). The problem of peroxynitrite damage is from not enough NO causing a delayed transition out of the superoxide dominated state.

Most of the problems due to a state of oxidative stress are not due to too much superoxide. The problems of oxidative stress are due to not enough NO. Superoxide is an anion and is blocked by lipid membranes. Virtually all superoxide is confined to where it is produced, in the inner matrix of mitochondria and inside microsomes. NO from outside the vesicle will diffuse in and be destroyed. It is NO that triggers the resumption of healing. If the NO level never comes back to “normal”, neither do the normal healing pathways. It is the lack of those healing pathways triggered by high NO that cause the accumulation of damage.

CFS is a chronic long term state. It needs to be dealt with in the chronic long term (until it is corrected). Treatments that cause short term subjective improvement need to be considered very carefully. An analogy I like to use is when a car has 100,000 miles, it starts to not run well because the engine is getting worn out. A salesman might induce the owner to use nitromethane as fuel. This will tremendously increase power in the short term, but will greatly accelerate wear and tear on the engine. An engine that might have been nursed along for another 50,000 miles might wear out in 100 while running on nitromethane. I see the use of stimulants to deal with the fatigue of CFS as analogous to this. Probably some herbal remedies (with unknown physiological effects) work this way. Increasing superoxide levels will give you the feeling of more energy in the short term because essential pathways can be turned off but will make the CFS worse. I consider it better to fix the root cause (not enough mitochondria) than come up with ways to drive existing mitochondria ever harder (which will make it worse).

Ways to increase NO levels. (But remember I am not a clinician so don’t take these as any type of medical advice)

Because NO is used as a signaling molecule in so many different pathways (hundreds or thousands), it is under intense physiologic regulation. It is extremely difficult to perturb NO/NOx physiology in the long term. It is virtually impossible to do so without causing adverse side effects. It is simply too complicated, too well controlled by too many redundant systems under too many different time, length and concentration scales in too many different tissue compartments to achieve acceptable control by external open-loop control (taking a pill x times a day).

Inhaled NO is used at ~20 ppm to prevent pulmonary hypertension and improve the matching of perfusion of blood with air exchange in the lung, especially in premies. Your nasal passages normally make a few hundred ppb to do exactly this. This only has local effects in the lung because the oxyhemoglobin in blood destroys NO in milliseconds. This can only be administered in a hospital setting.

“NO donors” have been suggested, but NO/NOx chemistry is more complicated than most researchers appreciate. Nitroglycerine has been called an NO donor, it is not. It does have some NO/NOx effects, but the precise mechanisms are not well understood. It likely has to do with generation of NO/NOx species in mitochondria, but at the expense of mitochondria aldehyde dehydrogenase (which is destroyed). This is thought to be the mechanism behind what is called “nitrate resistance” where people lose the ability to respond therapeutically to nitroglycerine. Nitroglycerine does cause migraines, and does cause oxidative stress. It may be exerting more of a long term “anti-NO” effect following a short term “NO effect” because of compensatory rebound. Some NO donors (such as sodium nitroprusside) do work as NO donors, but because NO has such a short lifetime (less than a minute), it must be administered continuously and intravenously and again, only in a hospital setting.

Diet: A good diet is obviously important to good health, but consumption of nutrients in excess of needs has never been shown to be advantageous. CFS is characterized by oxidative stress, but all the large, long-term, double blind, placebo controlled studies of supplemental antioxidants have shown no positive effects on health, and perhaps slight negative effects. My interpretation of this research is that there is an “oxidative stress” setpoint, and that physiology modulates itself to achieve that setpoint. The results from retrospective studies show that self-selected diets rich in green leafy vegetables are associated with good health, but which is cause and which is effect remains unknown. I think that self-selected diet choice may be a control parameter that physiology uses to modulate its state of oxidative stress. If the setpoint calls for oxidative stress, it is better to eat a diet devoid of antioxidants so that physiology doesn’t need to destroy them by generating more superoxide (which physiology has an unlimited capacity to do). This makes sense, if an organism needs to enter the “fight or flight” state, it can’t allow what it ate a few hours before impede that. If an organism is already in a state of oxidative stress, better to not eat anything that makes that state harder to maintain.

L-arginine is the substrate for nitric oxide synthase and is necessary for NO generation. NO generated by NOS is a signal. Some of it does spill over and become part of the basal NO background. However there are feedback mechanisms that limit the NO production by NOS, including production of NOS inhibitors (asymmetrical dimethyl arginine) and generation of more superoxide that counters the increased NO from increased L-arginine. Short term L-arginine supplementation does have positive effects on NO mediated disorders. The very few long term supplementation trials do not show improvement over placebo (which I think is likely due to compensation). You need to change the setpoint and consumption of exogenous supplements doesn’t do that.

Sildenafil (Viagra). This is not an NO donor, it can potentiate some effects of NO. A major pathway for NO is the activation of soluble guanylyl cyclase and the formation of cGMP. This cGMP relaxes smooth muscle and by doing so sets the vascular tone, and also activates the mechanism that causes erections. When sGC is activated an enzyme (PDE5) is produced that destroys cGMP and so regulates its concentration. Viagra inhibits that enzyme and so increases the amount and lifetime of the cGMP produced by sGC. Only some effects of NO are mediated through cGMP. There is a feedback circuit that down regulates the NO produced when the level of cGMP goes up. With PDE5 inhibited, there is still enough cGMP to produce effects mediated through cGMP. However there is less NO produced, so there are less of the other effects of NO mediated through non-cGMP effects. There was a trial where a single dose of Viagra exacerbated obstructive sleep apnea. There are rare reports of non-arteritic anterior ischemic optic neuropathy associated with use of PDE5 inhibitors. Viagra also causes migraines. I suspect that these side effects are due to feedback inhibition of NO production.

If Viagra did “cure” CFS, that would be readily apparent. It hasn’t been reported, and there isn’t anything in the physiology behind how Viagra works to suggest (to me) that it might. It does interfere with NO physiology in ways that are not completely understood. I suggest that its use be kept to a minimum, that is only for its prescribed indications and then at the minimum dose that is effective while being vigilant for neurological or other side effects. People with CFS may be more susceptible to those side effects due to compromised NO and mitochondria status.

A source of NO/NOx that is under physiologic control (to some extent) is consumption of nitrate in the form of green leafy vegetables. Lettuce and spinach and other green leafy vegetables have a few thousand ppm nitrate in them. This nitrate is well absorbed, and is concentrated in the saliva ~10x over plasma levels. There are commensal bacteria on the tongue that reduce this nitrate to nitrite, when the nitrite is swallowed the low pH in the stomach results in the formation of NO and this NO does have measurable physiological effects. Whether this would help CFS is unknown. The half life of nitrate is pretty short, ~8 hours so lettuce should be consumed (couple hundred grams) multiple times per day, and (probably) within a few hours before sleep (to have high NO/NOx levels during sleep).

Meditation is a method that has been shown to raise NO levels, as do other forms of stress reduction such as the Relaxation Response. Particularly the type of meditation practiced by the Dali Lama, one of beneficent mindfulness. This is essentially the neurogenic production of NO to switch physiology out of the “fight or flight” state. Not all forms of meditation are the same, I suspect what is called Kundalini Syndrome is similar to a permanent state of flight or flight.

Many positive social pathways are mediated through NO. Maternal bonding is mediated through NO. If NOS is inhibited ewes don’t bond to their lambs. In mammals maternal bonding has to be coupled to energy status because lactation is so energy intensive. That coupling is mediated through NO. I suspect that positive social interactions will increase NO levels by invoking the nurturing NO mediated pathways. In effect trying to invoke the opposite of the “fight or flight” state. Volunteering and doing things that help other people would likely invoke these same pathways and be, as a friend used to say, “Good and good for you”.

In summary, I see CFS as the consequence of low NO skewing the physiology into a permanent “fight or flight” state. The only way I know to get out of that state is to restore basal NO levels long enough for physiology to remodel itself into the low stress state.

This entry was posted on Friday, November 7th, 2008 at 3:31 pm and is filed under Treatments. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.