Open AccessVasomotor effect of histamine on pig and cattle coronary artery in vitro.
Author(s) -
Takeshi Obi,
Mitsuharu Matsumoto,
Akira Nishio
Publication year - 1991
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.55.311
Subject(s) - histamine , cimetidine , vasomotor , dimaprit , coronary arteries , vasoconstriction , histamine receptor , artery , medicine , diphenhydramine , endothelium , endocrinology , histamine h1 receptor , receptor , biology , antagonist
Vasomotor effects of histamine were examined in isolated coronary arteries from pigs and cattle. Histamine produced a concentration-dependent contraction in these arteries. These contractile responses were dose-dependently inhibited by diphenhydramine. The slopes of the Schild plots, however, were significantly lower than unity in both species. Cimetidine potentiated the histamine-induced contractions at relatively high doses of histamine (larger than 10(-5) M) in pig coronary arteries, but did not show a significant effect in cattle arteries. After the removal of endothelium, the Schild plot of diphenhydramine against histamine gave a straight line with a pA2 value of 7.80 and slope of 1.00 in pigs, confirming the competitive nature of the antagonism. In cattle, the slope was significantly lower than unity; however, in the presence of cimetidine, it was not significantly different from unity. Dimaprit did not contract the cattle coronary arteries with endothelium, but contracted them after the removal of endothelium. These results suggest that histamine-induced vasoconstriction in pig and cattle coronary arteries is mainly dependent on the H1-receptors in the smooth muscle cells, and that H1- and H2-receptors in the endothelial cells of pigs and H2-receptors in the smooth muscle cells of cattle modify the histamine-induced vasoconstrictions.