Abstract

One week after postganglionic denervation of the vas deferens there are marked changes in the response of the smooth muscle to stimulant drugs. The dose-response curve to norepinephrine in the denervated vasa, as determined in vitro, lies to the left of the contralateral control curve (63-fold at the geometric mean ED5O) . The sensitivity increase also occurs to acetylcholine (3-fold), histamine (3.7-fold) and potassium (2.3-fold). One week after preganglionie denervation (decentralization), there is a moderate increase in sensitivity to norepinephrine (2.5-fold) as well as supersensitivity to histamine (2-fold). In the presence of 10^-5 M cocaine the sensitivity of the vas deferens to norepinephrine is increased (13-fold) but not to acetylcholine or histamine. After chronic denervation the maximum response of the tissue is increased by 30 to 50% to norepinephrine, acetylcimoline and histamine but not to potassium. Decentralization and cocaine did not alter the maximum contractile responses to drugs. There is also an increase in the duration of the response to all four stimulants after denervation. The nonspecificity suggests that part of this change involves a postsynaptic alteration but apparently a change different from that which results in postsynaptic supersensitivity, since this effect is not duplicated by decentralization.