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PRE‐ AND POSTJUNCTIONAL EFFECTS OF CLONIDINE‐ AND OXYMETAZOLINE‐LIKE COMPOUNDS IN GUINEA‐PIG ILEAL PREPARATIONS
Author(s) -
MALTA E.,
RAPER C.,
TAWA PAULINE E.
Publication year - 1981
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.1476-5381.1981.tb10429.x
Subject(s) - oxymetazoline , clonidine , guinea pig , pharmacology , chemistry , endocrinology , medicine , agonist , receptor
1 Noradrenaline and 28 imidazolidine (clonidine‐like) and imidazoline (oxymetazoline‐like) compounds with various phenyl ring substituents have been examined for their ability to inhibit responses to transmural stimulation and exogenous acetylcholine in ileal preparations from reserpine‐treated guinea‐pigs. 2 The bathing solution contained propranolol, mepyramine, cimetidine and desipramine to preclude interference with the responses by other than the α‐receptor‐mediated actions of the compounds. 3 In transmurally stimulated preparations the inhibitory response to noradrenaline is due to a combination of prejunctional α‐adrenoceptor stimulation and a postjunctional depressant effect that does not involve adrenoceptor activation. 4 Of the 28 imidazolidines and imidazolines studied, 21 inhibited transmurally elicited responses. In the various compounds studied this effect involved actions at pre‐ or postjunctional sites as indicated by (a) the frequency‐dependence of the inhibitory response, (b) its susceptibility to blockade by α‐receptor antagonists and (c) the relative concentrations required to inhibit responses to transmural stimulation and exogenous acetylcholine.