Endothelial Nitric Oxide Synthase and POTS

adreno

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Hypertension. 2005 Nov;46(5):1103-10. Epub 2005 Oct 3.

Endothelial NO synthase polymorphisms and postural tachycardia syndrome.

Garland EM1, Winker R, Williams SM, Jiang L, Stanton K, Byrne DW, Biaggioni I, Cascorbi I, Phillips JA 3rd, Harris PA, Rüdiger H, Robertson D.

Abstract
Postural tachycardia syndrome (POTS) is a heterogeneous disorder characterized by an excessive rise in heart rate and symptoms consistent with cerebral hypoperfusion in the upright position. NO produced by endothelial NO synthase is a significant factor in the regulation of blood flow. Genetic polymorphisms in the promoter region (T-786C) and exon 7 (E298D) of the NO synthase isoform 3 gene affect enzyme activity and have been associated with a number of cardiovascular diseases. Because some findings in POTS suggest aberrant NO-mediated functions, we postulated that the variant genotypes of these polymorphisms may increase the risk of developing POTS and correlate with more severe symptoms. We genotyped 136 patients with POTS (mean age 32.2+/-9.9 years; 46 men and 90 women) from Nashville, Tenn, and Vienna, Austria, and compared them with 191 healthy volunteers (mean age 29.1+/-8.0 years; 127 men and 64 women). Participants also underwent orthostatic testing with blood pressure, heart rate, and plasma norepinephrine measurements while supine and upright. The frequencies of the -786CC and 298DD genotypes were significantly lower in patients with POTS than in control subjects (odds ratio [OR], 0.28; 95% confidence interval [CI], 0.14 to 0.57; P=0.001 for -786CC; and OR, 0.44; 95% CI, 0.21 to 0.91; P=0.033 for 298DD). According to 2-locus genotype analyses, patients with -786CC and 298EE or 298ED experienced the largest changes in heart rate and plasma norepinephrine with standing. These results indicate that NO may influence the development of POTS and the severity of POTS symptoms.

PMID:16203873
Not sure if this was ever posted. It certainly fits with my experience that supplements which increase eNOS activity worsens my OI.

Full text here:
http://hyper.ahajournals.org/content/46/5/1103.long
 
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adreno

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Am J Physiol Heart Circ Physiol. 2011 Sep;301(3):H704-11. doi: 10.1152/ajpheart.00171.2011. Epub 2011 Jun 3.

Cutaneous constitutive nitric oxide synthase activation in postural tachycardia syndrome with splanchnic hyperemia.

Stewart JM1, Nafday A, Ocon AJ, Terilli C, Medow MS.

Abstract
Models of microgravity are linked to excessive constitutive nitric oxide (NO) synthase (NOS), splanchnic vasodilation, and orthostatic intolerance. Normal-flow postural tachycardia syndrome (POTS) is a form of chronic orthostatic intolerance associated with splanchnic hyperemia. To test the hypothesis that there is excessive constitutive NOS in POTS, we determined whether cutaneous microvascular neuronal NO and endothelial NO are increased. We performed two sets of experiments in POTS and control subjects aged 21.4 ± 2 yr. We used laser-Doppler flowmetry to measure the cutaneous response to local heating as an indicator of bioavailable neuronal NO. To test for bioavailable endothelial NO, we infused intradermal acetylcholine through intradermal microdialysis catheters and used the selective neuronal NOS inhibitor l-N(ω)-nitroarginine-2,4-L-diamino-butyric amide (N(ω), 10 mM), the selective inducible NOS inhibitor aminoguanidine (10 mM), the nonspecific NOS inhibitor nitro-l-arginine (NLA, 10 mM), or Ringer solution. The acetylcholine dose response and the NO-dependent plateau of the local heating response were increased in POTS compared with those in control subjects. The local heating plateau was significantly higher, 98 ± 1%maximum cutaneous vascular conductance (%CVC(max)) in POTS compared with 88 ± 2%CVC(max) in control subjects but decreased to the same level with N(ω) (46 ± 5%CVC(max) in POTS compared with 49 ± 4%CVC(max) in control) or with NLA (45 ± 3%CVC(max) in POTS compared with 47 ± 4%CVC(max) in control). Only NLA blunted the acetylcholine dose response, indicating that NO produced by endothelial NOS was released by acetylcholine. Aminoguanidine was without effect. This is consistent with increased endothelial and neuronal NOS activity in normal-flow POTS.

PMID:21642500
This study also drew the conclusion that eNOS and nNOS are increased in POTS.

Full text:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3191087/
 

adreno

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Nitric oxide (NO) is a putative neurotransmitter in the central nervous system, and is formed on demand through the conversion of l-arginine to l-citrulline by the enzyme nitric oxide synthase (NOS). There are three isoforms of NOS: the brain or neuronal form (nNOS), the endothelial form (eNOS), and the inducible form (iNOS). The last is formed under pathological conditions and is calcium-independent. In contrast, nNOS and eNOS are constitutive, with activation dependent upon a calcium-calmodulin complex which binds to NOS following an increase in intracellular calcium concentration (for reviews, see Yun et al. 1996; Stuehr 1997). Consequently, synaptic activity resulting in increased intracellular calcium concentration, such as occurs following N-methyl-d-aspartate (NMDA) glutamate receptor activation during long-term potentiation (LTP), stimulates NO production. This suggests a possible role for NO in the mechanisms of plasticity associated with learning and memory.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC311308/

So eNOS and nNOS are activated after an increase in intracellular calcium concentration. Links to channelopathy?
 

Sidereal

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Personally, calcium channel blockers make my OI vastly worse. High nitrate foods like beets raise my BP (paradoxically) and improve OI but the effect is short-lived and rapid tolerance develops (couple of weeks).
 

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adreno

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Interesting. I am not eating a whole lot of nitrite foods, though. It would seem, as suggested in the studies above, that eNOS is over expressed. I wish I knew how to reduce this expression. Barring that, hydroxocobalamin seems to help a little by mopping up excess NO.
 

Crux

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If we can find the source of Oxidative Stress that's causing the overexpression of eNOS, et al., good.

The eNOS becomes uncoupled, and the production of toxic NO products ensues.
 

adreno

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Interesting, again @Crux . I've never heard of eNOS uncoupling before. That would indicate that ROS leads to more ROS in a vicious circle. Or as they put here:

Many cardiovascular diseases and drug-induced complications are associated with - or even based on - an imbalance between the formation of reactive oxygen and nitrogen species (RONS) and antioxidant enzymes catalyzing the break-down of these harmful oxidants. According to the "kindling radical" hypothesis, the formation of RONS may trigger in certain conditions the activation of additional sources of RONS.
eNOS uncoupling in cardiovascular diseases--the role of oxidative stress and inflammation.

But wouldn't this uncoupling lead to less NO being produced, not more?

Overproduction of reactive oxygen species leads to oxidation of tetrahydrobiopterin (BH4), the essential cofactor of eNOS. In BH4 deficiency, oxygen reduction uncouples from NO synthesis, thereby converting eNOS to a superoxide- producing enzyme. Consequently, NO production is reduced and the pre-existing oxidative stress is enhanced, which contribute significantly to cardiovascular pathology.
Pharmacological prevention of eNOS uncoupling.
 

adreno

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Also, I do not suffer from hypertension, or any other symptom associated with eNOS uncoupling and low NO. In this abstract, things are explained more clearly:

Pharmacol Ther. 2013 Dec;140(3):239-57. doi: 10.1016/j.pharmthera.2013.07.004. Epub 2013 Jul 13.

Nitric oxide synthase inhibition and oxidative stress in cardiovascular diseases: possible therapeutic targets?
Rochette L1, Lorin J, Zeller M, Guilland JC, Lorgis L, Cottin Y, Vergely C.

Abstract
Nitric oxide (NO) is synthetized enzymatically from l-arginine (l-Arg) by three NO synthase isoforms, iNOS, eNOS and nNOS. The synthesis of NO is selectively inhibited by guanidino-substituted analogs of l-Arg or methylarginines such as asymmetric dimethylarginine (ADMA), which results from protein degradation in cells. Many disease states, including cardiovascular diseases and diabetes, are associated with increased plasma levels of ADMA. The N-terminal catalytic domain of these NOS isoforms binds the heme prosthetic group as well as the redox cofactor, tetrahydrobiopterin (BH(4)) associated with a regulatory protein, calmodulin (CaM). The enzymatic activity of NOS depends on substrate and cofactor availability. The importance of BH(4) as a critical regulator of eNOS function suggests that BH(4) may be a rational therapeutic target in vascular disease states. BH(4) oxidation appears to be a major contributor to vascular dysfunction associated with hypertension, ischemia/reperfusion injury, diabetes and other cardiovascular diseases as it leads to the increased formation of oxygen-derived radicals due to NOS uncoupling rather than NO. Accordingly, abnormalities in vascular NO production and transport result in endothelial dysfunction leading to various cardiovascular disorders. However, some disorders including a wide range of functions in the neuronal, immune and cardiovascular system were associated with the over-production of NO. Inhibition of the enzyme should be a useful approach to treat these pathologies. Therefore, it appears that both a lack and excess of NO production in diseases can have various important pathological implications. In this context, NOS modulators (exogenous and endogenous) and their therapeutic effects are discussed.
 

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@adreno , I used those terms even though they are more involved with reduced NO bioavailability rather than overexpression.

I ran across an article that compared a type of eNOS overexpression and uncoupling as,' trying to peddle a bicycle with a broken chain'. Couldn't find it again.

I'm more concerned with overproduction of NO itself and its pathology.

Here's a small study that used a general NOS inhibitor demonstrating that excessive NO was causing autonomic failure in a small group : http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2497433/

This article discusses the role of NO in immune response. It discusses the pro and anti inflammatory effects of NO.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3100761/

During acute inflammation, eNOS and iNOS mediate different effects depending on the type of injury. In experimental arthritis models involving streptococcal cell wall injections, eNOS was found to be deleterious, and iNOS activity was protective [240242]

Similarly, contrasting effects of NOS isoforms occur during IR injury, where eNOS is protective, but iNOS is detrimental. In most IR models, eNOS has a positive effect, and iNOS is associated with toxicity. In part, this is because reperfusion injury focuses on the endothelium
 
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Lolinda

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Thanks @adreno for posting all this research! When I read such papers, I always ask myself: does it apply to me? Can I get a test done? I would like to get tested first for nitric oxide, to see if I have elevated levels at all, before entering all the details of so many possible causes. Now, all testing methods have advantages and disadvantages, but most often nitrate and nitrite are estimated in blood or urine. I would be already glad with a rough estimate if there is sthg grossly wrong in me.

Question to all researchers and research enthusiasts on PR: Do you give the following home test method a chance to deliver at least a very rough estimate?

- Use these nitrate & nitrite test stripes with serum or urine. In case of urine, divide by creatinine.
- Avoid sports and eat low nitrate for 3 days before the test (PM me if you need fulltext access, the 3 days are mentioned only in the fulltext)

The test stripes use the same reaction as is most often used in published research, that is, the Griess reaction. They are for complex biological substances ranging from aquarium water to soil.
 
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Here's a small study that used a general NOS inhibitor demonstrating that excessive NO was causing autonomic failure in a small group : http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2497433/
Very interesting.

This reminds me of Dr. Pall's OH/ONOO theory.
Indeed it does.

Quote below from Dr Myhill, which is fitting after reading that study:
Professor Martin Pall has looked at the biochemical abnormalities in CFS and shown that sufferers have high levels of nitric oxide and its oxidant product peroxynitrite. These substances may be directly responsible for many of the symptoms of CFS and are released in response to stress, whether that is infectious stress, chemical stress or whatever
 
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Interesting. I am not eating a whole lot of nitrite foods, though. It would seem, as suggested in the studies above, that eNOS is over expressed. I wish I knew how to reduce this expression. Barring that, hydroxocobalamin seems to help a little by mopping up excess NO.
"Astaxanthin inhibits nitric oxide"
http://www.ncbi.nlm.nih.gov/pubmed/14503852

These results suggest that astaxanthin, probably due to its antioxidant activity, inhibits the production of inflammatory mediators by blocking NF-kappaB activation and as a consequent suppression of IKK activity and I(kappa)B-alpha degradation.
Also:
http://www.ncbi.nlm.nih.gov/pubmed/23100599

Astaxanthin feeding also increased (P<0.05) the reduced glutathione to oxidized glutathione ratio in young dogs and decreased (P<0.05) nitric oxide in both young and geriatric dogs. Dietary astaxanthin improved mitochondrial function in blood leukocytes, most likely by alleviating oxidative damage to cellular DNA and protein.
So alleviating oxidative damage improves mitochondrial function? Isn't that the goal of Dr Pall?
 

Lolinda

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I was very interested in Pall's approach, so I got tested. Fortunately, these tests are relatively easy to obtain, labs usually offer them under names such as "nitrosative stress". Nitrosative stress is exactly the free radical damage (=oxidative stress) brought about by NO/ONOO. Here are two entirely different testing approaches, offered in Europe by Redlabs.be and by ganzimmun.de and some others. In the US, there is a subsidiary of Redlabs, you find them over their homepage. The Ganzimmun-style test should be really easy to find in the US or UK or wherever you are from. I did far too much readings on these things, just lost my time, should have got tested immediately, so I had known earlier that I do not have any nitrosative stress at all....

While nitrosative stress is easy to test, nitric oxide is a topic in its own right and is not easy to test at all. I directly asked the labs if any of these tests shown below allow any conclusions about nitric oxide. No, they dont. It works like this: Free radical damage, that is, nitrosative stress, occurs only if there is a process called NO uncoupling. Elevated NO may deplete BH4 and make uncoupling more likely to happen, but doesn't cause nitrosative stress in itself.
-> These tests below are fine to rule out the NO/ONOO issue, but are not ruling out elevated NO in itself. I would be so glad to find a good test for NO! Testing would be really important as NO (without nitrosative stress) is actually very useful and supporting health. I do not like so much the idea of lowering it without knowing if I have too much. In fact, most people woud be glad to increase their NO (cardiovascular diseases, athletes, etc).

redlabs.be:
IMG_20160919_092606.jpg

ganzimmun.de in Germany and labor team W in Switzerland:
IMG_20160919_092223.jpg
 
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I tested 8mg of Astaxanthin, and I see no difference in my POTS. Who knows, it was just one day and I don't plan to keep taking it.

Stuff that seems awesome on paper often doesn't match the same awesomeness in actuality.
 
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JES

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I would be so glad to find a good test for NO! Testing would be really important as NO (without nitrosative stress) is actually very useful and supporting health. I do not like so much the idea of lowering it without knowing if I have too much. In fact, most people woud be glad to increase their NO (cardiovascular diseases, athletes, etc).
NO has a blood half-life of a couple of seconds, so I assume it would be impossible to measure it in a standard blood test, at least not reliably. Nitrite and nitrate levels would be easier to measure since they have a longer half life, and since they participate in the NO cycle they are some kind of indicators for NO activity.
Stuff that seems awesome on paper often doesn't match the same awesomeness in actuality.
Exactly. Astaxanthin is a super antioxidant, no doubt, but I don't see much other specific benefits in it for CFS/ME. I responded to it in similar way as to most other antioxidants, in short term it improved my symptoms, in long term it worsened my fatigue. It doesn't seem much different as alpha-lipoic acid etc.
 

Lolinda

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NO has a blood half-life of a couple of seconds, so I assume it would be impossible to measure it in a standard blood test, at least not reliably. Nitrite and nitrate levels would be easier to measure since they have a longer half life, and since they participate in the NO cycle they are some kind of indicators for NO activity
Exactly! That is what I mean by "NO testing". I cited studies in my post above, most of their measurement methods relying on nitrate/nitrite. But I have found so far only a bogus lab (ELN in the Netherlands) that offers a test commercially (and they tell you to send in the sample unfrozen, it will be fine... not only that NO has a half-life of seconds, but nitrate and nitrite arent that stable either).

I responded to it in similar way as to most other antioxidants, in short term it improved my symptoms, in long term it worsened my fatigue
You are the first person whom I see writing this. I have that too, very similar! I always wondered that so many people are enthusiastic about ALA... But in me it is first improvement, then worsening. It was like that when I had ME (meanwhile resolved). Now, where "only" POTS and neuropathy is left, the nature of improvement and worsening is a bit different, but the pattern is the same. Currently it is that in the first wave of improvement (few days), a "heavenly peace" comes upon me. And the best part of it is that I feel like doing everything with minimal effort and big effect. And a peaceful wisdom in my mind. Really wow, so good! But at the same time sleeping issues increase day by day until I better stop ALA after a few more days. Btw on the first day with ALA, my neuropathy got better too (less stinging pains).

I wonder, what was your ALA dose? (Mine: 2 x 200mg)
Did you try ALA in low doses to see if it is better?
Do you have any explanation for all this up and down?
 
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JES

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You are the first person whom I see writing this. I have that too, very similar! I always wondered that so many people are enthusiastic about ALA... But in me it is first improvement, then worsening. It was like that when I had ME (meanwhile resolved). Now, where "only" POTS and neuropathy is left, the nature of improvement and worsening is a bit different, but the pattern is the same. Currently it is that in the first wave of improvement (few days), a "heavenly peace" comes upon me. And the best part of it is that I feel like doing everything with minimal effort and big effect. And a peaceful wisdom in my mind. Really wow, so good! But at the same time sleeping issues increase day by day until I better stop ALA after a few more days. Btw on the first day with ALA, my neuropathy got better too (less stinging pains).

I wonder, what was your ALA dose? (Mine: 2 x 200mg)
Did you try ALA in low doses to see if it is better?
Do you have any explanation for all this up and down?
I trialed ALA a couple of times in 2014, it somehow gave me hypogylacemia which was the primary reason I stopped taking it, I reckon I never did more than 200mg.

But yeah, I do have this worsening reaction to almost every antioxidant I've tried, my CFS symptoms go from mild to moderate while on them in a matter of less than a week. I don't have POTS diagnosed, but I notice that my standing heart rate is much increased after being a couple of days on a strong antioxidant, it even causes some skipped beats. My chronically cold hands also tend to get worse. I wouldn't be surprised if all this is related to the NO cycle, as antioxidants tend to lower NO levels, which seems to result in worsening for me.
 

Lolinda

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I trialed ALA a couple of times in 2014, it somehow gave me hypogylacemia which was the primary reason I stopped taking it, I reckon I never did more than 200mg.
.
Thank you!! That fully answers the issue!! I just double-checked and yes, ALA lowers blood sugar:
http://umm.edu/health/medical/altmed/supplement/alphalipoic-acid
"Several studies suggest alpha-lipoic acid helps lower blood sugar levels."

And this fully explains my sleeping issues: if blood sugar goes down -> cortisol goes up -> no sleep.
I add that my blood sugar is just barely enough as I am on a very low carb diet. I need that, because that is what got me out of bad ME and what keeps me out of it. Lowering blood sugar further is no good. Thanks a lot for your post, which helped me to discover why ALA causes bad sleep in me!!

But then there are the good things, which I want:
"Its ability to kill free radicals may help people with diabetic peripheral neuropathy, who have pain, burning, itching, tingling, and numbness in arms and legs from nerve damage."
(I dont have any diabetes, but do have axonal neuropathy)

--> I will take next a small dose, maybe 100mg in the early morning, so that the effect fades off till night.

And for your case: if you think of hypoglycaemia, there is an easy way to combat that: eat more healthy fats (olive oil, lard, butter, coconut oil). This sounds paradox but it works, because fat is a long lasting continuous source of energy and does not cause blood sugar fluctuations, insulin spikes, etc.
(Remark: The situation I describe for myself, i.e. barely enough blood sugar, occurs only if you are on a very low carb diet, that is, in ketosis. - I am and I profit greatly. )
- But this is just a minor side comment. More importantl comment:

Regarding antioxidants and NO: Have you checked for all sorts of infections? Antioxidants are bad if you have an infection, because it is oxidants, that is free radicals, how your body fights the infections! Equally, nitric oxide should not at all be lowered but increased in infections, it fights them well!
- OK I guess much of this you already know... You seem really well-informed from your comments. But if there is only a single new idea I could give, then I am glad.
The only "antioxidant" I would take when fighting Infections is vitamin C... It is just as much a pro-oxidant...

btw cold limbs sounds to me like too little NO, to start with....
And you could try for that:
- eat lots of grean leaves (parsley, cilantro,spinach,...)
- here sbdy makes the point that thebacteria in AOmist convert ammonia to nitrite. Which is exactly what ammonia oxidising bacteria should do
 
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