EFFECT OF ENKEPHALIN AND SUBSTANCE P ON SYMPATHETIC NERVE TRANSMISSION IN MOUSE VAS DEFERENS

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Abstract
Effect of methionine-, leucine-enkephalin (met-, leu-enkephalin) and substance P on the transmission in mouse vas deferens was studied. Both met- and leu-enkephalin inhibited electrically induced contraction of vas deferens at 10-8-10-7 M, met-enkephalin being 1.4 times more active than leu-enkephalin. Nalorphine (10-6 M) antagonized these effects. Substance P (10-9-10-7 M) had no effect on the contraction. Met- and leu-enkephalin (10-7-10-5 M) decreased the high K induced [3H]-norepinephrine release from vas deferens, while substance P (10-5 M) significantly increased it. Nalorphine (10-5 M) reversed the inhibitory effect of met-enkephalin. These peptides might modify the transmission of sympathetic nerve in mouse vas deferens.