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DIFFERENTIATION OF THE ROLES OF HISTAMINE H r AND H 2 ‐RECEPTORS IN THE MEDIATION OF THE EFFECTS OF HISTAMINE IN THE ISOLATED WORKING HEART OF THE GUINEA‐PIG
Author(s) -
FLYNN SHEILA B.,
GRISTWOOD R.W.,
OWEN D.A.A.
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.tb17341.x
Subject(s) - dimaprit , histamine , cimetidine , mepyramine , histamine receptor , histamine h2 receptor , histamine h1 receptor , medicine , endocrinology , agonist , histamine h4 receptor , chemistry , pharmacology , receptor , biology , antagonist
1 Differentiation of the rôles of histamine H r and H 2 ‐receptors in the mediation of the effects of histamine on the isolated working heart of the guinea‐pig was achieved through the use of histamine and selective histamine receptor agonists and antagonists. 2 Histamine over the dose range 10 −9 mol to 10 −6 mol produced dose‐related increases in sinus rate, left intraventricular pressure (LVP) max , LVdP/dt max , coronary flow, aortic flow, total cardiac output and external pressure‐volume work. 3 Dimaprit, a selective histamine H 2 ‐receptor agonist, produced very similar responses to histamine. 4 2‐Pyridylethylamine, a selective histamine Hj‐receptor agonist, had little effect on cardiac function unless large doses were administered. Such doses produced increases in all measured parameters. 5 Cimetidine, a selective histamine H 2 ‐receptor antagonist, antagonized the effects of histamine and dimaprit and some but not all effects of 2‐pyridylethylamine. In the presence of cimetidine a decrease in all parameters with the exception of sinus rate was observed with both histamine and 2‐pyridylethylamine. 6 The selective histamine Hi‐receptor antagonist, mepyramine, had little effect on responses to all three agonists. However, the depressant effects observed with histamine and 2‐pyridylethylamine in the presence of cimetidine were antagonized by mepyramine. 7 The results indicate the important rôle of the histamine H 2 ‐receptor in the mediation of the gross cardiac effects of histamine and also indicate that histamine H x ‐receptors can mediate cardiac depression.