What is true in a blood vessel about cholinergic vasodilatation?

[Nabin]

Two statements:

1. Blood vessels don't have cholinergic innervation, but have M receptors mediating dilatation via acetylcholine (NO mechanism)

2. Blood vessels have some sympathetic cholinergic innervation with acetylcholine as neurotransmitter mediating vasodilation (NO mechanism)

Which one is true?

Why does atropine cause facial flushing?

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[tpsreport]

Atropine inhibits the cholinergic innervation of your sweat glands. Because you can't sweat, your body compensates by dilating the blood vessels in order to use conduction and convection as a means of heat dispersal rather than evaporation. Your face is highly vascularized, so that's why atropine causes facial flushing.

What do you mean by 'NO mechanism'? Are you talking about cyclic GMP mediated? If so the only ones that are cGMP mediated that I know of are NO, ANP, BNP, etc. Ach acts via nicotinic, and M1-M5.

 

[Nabin]

Atropine inhibits the cholinergic innervation of your sweat glands. Because you can't sweat, your body compensates by dilating the blood vessels in order to use conduction and convection as a means of heat dispersal rather than evaporation. Your face is highly vascularized, so that's why atropine causes facial flushing.

What do you mean by 'NO mechanism'? Are you talking about cyclic GMP mediated? If so the only ones that are cGMP mediated that I know of are NO, ANP, BNP, etc. Ach acts via nicotinic, and M1-M5.

Thanks. I was trying to know if a specific drug-mediated process was involved in the cutaneous vasodilation. So, that is out of the way. Hence it got me confused with the atropine fever mechanism.

On the latter part, yes I was talking about that. Uworld mentions that acetylcholine mediated vasodilation occurs in blood vessels by increasing eNOS synthesis in the endothelium. Blood vessels, without any cholinergic innervation, still have some M receptors so they respond in that way. I don't remember another source but I feel I had studied 'somewhere' that there is some sympathetic cholinergic innervation to the blood vessels. So, either blood vessels have only some M receptors or there is some sympathetic cholinergic innervation too? I wanted to make sure.