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The effect of isoprenaline on adrenoceptors in human saphenous vein
Author(s) -
COUPAR I. M.
Publication year - 1970
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.1476-5381.1970.tb10355.x
Subject(s) - isoprenaline , vein , medicine , cardiology , chemistry , stimulation
1 The order of potency of sympathomimetic amines in causing contraction of strips of human saphenous vein was (−)‐adrenaline>(−)‐noradrenaline>(−)‐phenylephrine>(±)‐isoprenaline. 2 The competitive α‐adrenoceptor blocking drugs tolazoline, phentolamine, and thymoxamine and the irreversible blocking drug phenoxybenzamine all blocked noradrenaline and isoprenaline contractions. 3 Contractions produced by 5‐hydroxytryptamine were also blocked by phentolamine and thymoxamine. Fenfluramine‐induced contractions were not blocked by thymoxamine or phenoxybenzamine. 4 ED50 contracting doses of isoprenaline did not cause consistent relaxation of noradrenaline‐contracted strips. 5 It is concluded that human saphenous vein contains a dominant population of α‐adrenoceptors which can be stimulated by high doses of isoprenaline, but the occurrence of β‐adrenoceptors mediating relaxation is rare.