I have read this article on physiology of erection :

Activation of cholinergic receptors on the endothelial cell by acetylcholine or stretching of the endothelial cells as a result of increased blood flow may elicit underlying smooth muscle relaxation through the release of NO.

I know erection is caused by parasympathetic outflow; but how come the cholinergic receptors on the endothelial cells are activated by aCh because there are no parasympathetic neuronal endings on endothelium, as from what I've learned and there could not be aCh freely released in penile arteries because butrylcholinesterase in blood would inactivate the aCh?

I understand that the corpora cavernosa are relaxed to help sinusoids accumulate blood and corpora spongiosum are contracted to prevent venous outflow of the blood to maintain the erection.

  • $\begingroup$ ACh is released onto blood vessels and affects receptors on smooth muscle and endothelium. Can you cite your assertion that this doesn't occur? $\endgroup$
    – Bryan Krause
    Nov 5 '18 at 20:41
  • 1
    $\begingroup$ You may be confused because most peripheral blood vessels do not have direct parasympathetic innervation. The pelvic region is unique here (pelvic blood vessels do have direct parasympathetic innervation) $\endgroup$
    – De Novo
    Nov 5 '18 at 20:56
  • $\begingroup$ @DeNovo Maybe not quite unique, but "special" perhaps? $\endgroup$
    – Bryan Krause
    Nov 5 '18 at 21:07
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    $\begingroup$ @BryanKrause yes, you're right. Lets go with special. $\endgroup$
    – De Novo
    Nov 5 '18 at 21:18
  • $\begingroup$ @DeNovo I've got my answer then. $\endgroup$
    – user73023
    Nov 6 '18 at 6:17

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