Abstract
The supersensitivity of the smooth muscle of the vas deferens which occurs to norepinephrine after postganglionic denervation is believed to be due to a combination of prejunctional (loss of neuronal uptake) and postjunctional changes. Evidence obtained in this study indicates that the increase in sensitivity to acetylcholine after denervation also has a prejunctional component (an inhibition of cholinestenase activity) but that the contribution of this component to the total increase in sensitivity to acetylcholine is small. Seven days after denervation, a time at which there is a 50-fold increase in sensitivity of the smooth muscle to acetylcholine, there is a marked inhibition (55%) in the hydrolysis of radiolabeled acetylcholine and methacholine by homogenates of vasa deferentia. Twenty-four hours after the administration of disulfoton (5 mg/kg), an organophosphorus cholinesterase inhibitor, there was only a 2-fold increase in the sensitivity of the smooth muscle to acetylcholine, but an inhibition of cholinesterase activity equivalent to that produced by denervation. The sensitivity of the smooth muscle to carbachol. a nonhydrolyzable ester, was increased by denervation (65-fold) but not by disulfoton.
Footnotes
- Received July 16, 1973.
- Accepted January 14, 1974.
- © 1974 by The Williams & Wilkins Co.
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