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Impromidine is a partial histamine H 2 ‐receptor agonist on human ventricular myocardium
Author(s) -
English T.A.H.,
Gristwood R.W.,
Owen D.A.A.,
Wallwork J.
Publication year - 1986
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.1476-5381.1986.tb10265.x
Subject(s) - histamine , mepyramine , cimetidine , endocrinology , medicine , histamine h2 receptor , inotrope , chemistry , dimaprit , agonist , histamine h1 receptor , receptor , biology , antagonist
1 The inotropic effects of impromidine have been studied and compared with those of histamine on human isolated left ventricular preparations stimulated at 1 Hz. Both drugs caused concentration‐related increases in force of contraction and were of similar potency, although the maximum response to impromidine was markedly and significantly less than that to histamine. 2 The positive inotropic responses of impromidine were inhibited by cimetidine 1 × 10 −5 M, consistent with histamine H 2 ‐receptor involvement. 3 Impromidine 1 × 10 −4 M inhibited maximal responses to histamine to a level equal to the maximal impromidine response; however, impromidine did not inhibit responses to isoprenaline. 4 Positive inotropic activity and inhibition of maximal responses to histamine occurred over a similar impromidine concentration‐range. 5 Impromidine displaced histamine concentration‐response curves to the right, whereas mepyramine had no effect on responses to histamine. 6 It is concluded that impromidine has positive inotropic activity on the human ventricle, that the response is mediated via histamine H 2 ‐receptors, and that impromidine is a partial agonist compared with histamine.