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Histamine‐induced changes in coronary circulation and myocardial oxygen consumption: influences of histamine receptor antagonists
Author(s) -
Kang Y. H.,
Wei H. M.,
Fisher H.,
Merrill G. F.
Publication year - 1987
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.1.6.3678703
Subject(s) - chronotropic , histamine , cimetidine , inotrope , medicine , vasoconstriction , diphenhydramine , endocrinology , chemistry , heart rate , blood pressure
The effects of histamine and selected H 1 and H 2 histamine receptor antagonists on cardiac inotropic and chronotropic activity, coronary perfusate flow (CPF), and myocardial oxygen consumption MV ˙O 2were studied in isolated guinea pig hearts perfused at constant pressure. Data were collected at the end of a 3‐min infusion period at steady state. Cardiac performance increased significantly whereas CPF decreased during histamine infusion. MV ˙O 2remained constant owing to a significant increase in myocardial oxygen extraction. Diphenhydramine attenuated the coronary vasoconstriction but potentiated the positive inotropic response. Cimetidine attenuated the inotropic and chronotropic responses but had no effect on coronary vasoconstriction. In combination, the histamine antagonists attenuated the changes in heart rate, contractility, and CPF. The histamine‐induced increase in myocardial oxygen extraction was accompanied by a significant increase in MV ˙O 2in the presence of diphenhydramine. The ratio of the change in oxygen extraction to the change in oxygen consumption caused by histamine was significantly increased by diphenhydramine. This compensated for a histamine‐induced decrement in the ratio of the change of CPF to the change in oxygen consumption. Cimetidine had no effect on the changes in coronary flow, oxygen consumption, or the above ratios. Thus, histamine causes direct coronary vasoconstriction via an H 1 receptor mechanism, cardiac positive inotropy by an H 2 receptor mechanism, and cardiac positive chronotropy by combined H 1 and H 2 mechanisms. In the presence of a histamine‐induced decrease in myocardial oxygen supply, increments in oxygen demand are met by increased oxygen extraction.— K ang , Y. H.; W ei , H. M.; F isher , H.; M errill , G. F. Histamine‐induced changes in coronary circulation and myocardial oxygen consumption: influences of histamine receptor antagonists. FASEB J. 1: 483‐490; 1987.