In vitro effect of acetylcholine and bethanechol on the contractions of the human detrusor muscle. Influence of prostaglandins.

The effects of acetylcholine and bethanechol on the basal resting tone of the isolated detrusor muscle were explored. It was observed that the tone was augmented by both agents. On the other hand, in the presence of prostaglandin (PG)-inhibitors the dose-response curve of acetylcholine shifts to the right. PGF 2 alpha (10(-10)M) but not PGE2 (10(-10)M) completely blocked the inhibitory effect of PG-inhibitors upon the inotropic effect of acetylcholine, without modifying the influence of bethanechol. After inhibitors of PG-synthesis, eserine abolished the inhibitory action of acetylcholine but did not change the influence of bethanechol. Our results suggest that endogenous PGs facilitate the action of acetylcholine through an increase in the concentration of the cholinergic neurotransmitter probably via an inhibition of the acetylcholinesterase activity.