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SINGLE PULSE STIMULATION OF GUINEA‐PIG VAS DEFERENS AND THE PRESYNAPTIC RECEPTOR HYPOTHESIS
Author(s) -
KALSNER STANLEY
Publication year - 1979
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1979.tb13686.x
Subject(s) - phenoxybenzamine , vas deferens , stimulation , medicine , guinea pig , endocrinology , adrenergic , blockade , chemistry , neuroscience , receptor , biology
1 The effect of phenoxybenzamine on the efflux of [ 3 H]‐noradrenaline and the mechanical response to single pulse excitation of superfused guinea‐pig vas deferens was determined to examine the validity of the currently accepted hypothesis of a presynaptic negative feedback system on adrenergic nerve terminals. 2 The adrenoceptor antagonist enhanced both the outflow of tritium and the mechanical response to single pulse stimulation. The efflux of labelled material and the responses to 4 pulses were also enhanced, as expected. 3 Blockade of neuronal and extraneuronal uptake did not by itself increase nerve‐induced outflow or the mechanical response nor did it prevent phenoxybenzamine from doing so. 4 The present observations cannot be accommodated within the framework of a hypothesis that proposes that the enhancement of response and tritium efflux by phenoxybenzamine results from blockade of a feedback system whereby noradrenaline released by previous impulses inhibits its own subsequent release.