EFFECTS OF ACETALDEHYDE ON CONTRACTILE RESPONSE TO NERVE-STIMULATION IN GUINEA-PIG VAS-DEFERENS

Twitch contractions of the isolated guinea-pig vas deferens induced by sympathetic nerve stimulation were augmented by acetaldehyde (0.1-10 mM). With high concentrations (5-10 mM), acetaldehyde produced a biphasic response consisting of an initial brief depression and a subsequent potentiation of the contraction. The late effect was associated with repetitive contractions that were not prevented by tetrodotoxin. A low concentration of phentolamine (27 μM) increased and a high concentration (1.3 mM) suppressed the potentiating action of acetaldehyde. Acetaldehyde did not induce contractions in surgically sympathectomized vasa or vasa pretreated with reserpine. Acetaldehyde caused a dose-dependent increase in noradrenaline release into the bathing fluid. The study shows that acetaldehyde has a dual effect on sympathetic neuroeffector tranmission, and that an increase in noradrenaline secretion appears to contribute to the late facilitatory effect in the isolated vas deferens. © 1990.