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THE ROLE OF H 1 AND H 2 ‐RECEPTORS IN THE CORONARY VASCULAR RESPONSE TO HISTAMINE OF ISOLATED PERFUSED HEARTS OF GUINEA‐PIGS AND RABBITS
Author(s) -
BROADLEY K.J.
Publication year - 1975
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.1476-5381.1975.tb07599.x
Subject(s) - chronotropic , mepyramine , vasoconstriction , histamine , vasodilation , medicine , inotrope , coronary perfusion pressure , coronary vasodilator , endocrinology , coronary circulation , coronary vessel , receptor , cardiology , heart rate , anesthesia , hemodynamics , blood pressure , blood flow , antagonist , cardiopulmonary resuscitation , resuscitation
1 The effects of histamine on the isolated perfused hearts of guinea‐pigs and rabbits were examined. Records of contractile force, heart rate and coronary perfusion pressure were obtained. 2 Histamine exerted positive inotropic and chronotropic effects which were antagonized by burimamide and attributed to stimulation of H 2 ‐receptors. 3 The coronary vascular response to histamine differed between guinea‐pigs and rabbits. In guinea‐pig hearts, three phases were apparent: (a) An initial vasodilatation preceding any effects on heart force and rate was antagonized by mepyramine and therefore mediated by histamine H 1 ‐receptors in the coronary circulation. (b) A secondary vasoconstriction was attributed to the increased myocardial compression during the positive inotropic and chronotropic responses. (c) The final, more predominant, component was a prolonged vasodilatation probably associated with the increased metabolic activity of the heart. 4 The latter two components were abolished together with the myocardial responses by burimamide. The remaining coronary vascular response was biphasic, consisting of a vasodilatation immediately followed by vasoconstriction. Both were antagonized by mepyramine and therefore mediated by H 1 ‐receptors. 5 The coronary vascular response of rabbit hearts was similar but no direct vasodilatation was observed and it was concluded that histamine receptors in the coronary vasculature involve only vasoconstriction.