I get a lot of PM's about physiology: why things work the way they do in the body. I would like to have a place where people can ask that kind of question and I'll do my best to answer so everyone can read the answer. I will reduce the repeat answers in pm for me
Here is one I got recently:
reading over the threads on vasodilation again I'm getting confused about something very basic: why is vasodilation good? If it affects mostly the arteries one would imagine pressure building up toward the veins, or not?
Also, do you remember whether Niacin flush has ever been brought up?
That is a good question . The issue regarding any vasodilators is that they impact the arteries a lot more than the veins. Arteries have smooth muscles are strong thick vessels where veins are thin and passive. Arteries have to withstand the pulse, veins barely feel it at all because they are on the other side of the capillary bed. Vasoconstriction though is bad for the CCSVI paradigm as it would restrict blood flow a little more and we are already looking at hypoxic circumstances, therefore the idea of dilators ends up being preferable.
Niacin is a potent temporary vasodilator (as long as you get the regular kind not the no flush kind) and we have discussed it with the same speculative "vigor"
The amyl nitrite research in which persons in relapse had a dramatic turn around in function makes you wonder if it might not help a person in relapse a little bit .
as for veins getting too much blood after the arteries open up, that is a speculation with regards to stenosis. In general with vasodilation the blood pressure drops....so more blood but less pressure. a flushing effect for the veins.