Parasympathetic Ganglia: Activation of an Adrenergic Inhibitory Mechanism by Cholinomimetic Agents
William R. Saum 1 and
William C. De Groat 1
1 Department of Pharmacology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
Electrical stimulation of the sympathetic nerves to the urinary bladder or the intraarterial administration of the cholinomimetic substances acetylcholine or methacholine produced adrenergic inhibition in parasympathetic ganglia on the surface of the bladder. The inhibition appeared to be mediated, at least in part, via adrenergic inhibitory neurons located in the pelvic plexus. Atropine blocked the inhibitory response to injected cholinomimetic agents but did not alter the response to stimulation of the sympathetic nerves. Thus, the inhibitory neurons can be activated via both muscarinic and nonmuscarinic receptors, the latter being of primary physiological importance.
