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EFFECTS OF METOCLOPRAMIDE AND ISOPRENALINE IN THE RAT VAS DEFERENS; INTERACTIONS WITH α‐ADRENOCEPTORS
Author(s) -
SPEDDING M.
Publication year - 1980
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.1476-5381.1980.tb10916.x
Subject(s) - vas deferens , phentolamine , isoprenaline , metoclopramide , propranolol , phenylephrine , endocrinology , medicine , chemistry , stimulation , antagonist , clonidine , adrenergic antagonist , pharmacology , blood pressure , receptor , vomiting
1 Metoclopramide (2.8 to 280 μ m ) augmented contractions of rat vas deferens preparations induced by field stimulation (6 Hz for Is). This effect was antagonized by phentolamine (0.1 μ m ). Metoclopramide (2.8 to 280 μ m ) did not affect phenylephrine‐induced contractions. 2 Metoclopramide (2.8 to 280 μ m ) antagonized the inhibitory effects of clonidine on the contractions induced by field stimulation, but not the inhibitory effects of purine nucleosides. 3 From these results it is concluded that metoclopramide (2.8 to 280 μ m ) is a presynaptic α‐adrenoceptor antagonist in the rat vas deferens. 4 Following β‐adrenoceptor blockade with (±)‐propranolol (3.3 μ m ), (‐)‐isoprenaline (0.47 to 14 μ m ) inhibited responses to field stimulation but not to phenylephrine. These propranolol‐resistant effects of isoprenaline were antagonized by metoclopramide (2.8 to 280 μ m ) and by phentolamine (0.1 to 10 μ m ), indicating that isoprenaline may stimulate presynaptic α‐adrenoceptors in this preparation.