Characteristics of histamine receptors in the isolated and perfused canine coronary arteries.
The vascular responses of isolated and perfused canine epicardial coronary arteries to histamine, 2-pyridylethylamine (2-PEA, a selective histamine H1-receptor agonist) and dimaprit (a selective histamine H2-receptor agonist) were studied. Histamine produced only a vasodilatation at small doses (less than 0.3 microgram) and a biphasic response, i.e., vasoconstriction followed by vasodilatation at large doses. 2-PEA produced only a vasoconstriction at small doses and at large doses a slight vasodilatation following vasoconstriction. Dimaprit usually induced only a vasodilatation. The selective histamine H1-receptor antagonist chlorpheniramine shifted the dose-response curves of histamine and 2-PEA for inducing vasoconstriction to the right. Cimetidine (a selective histamine H2-receptor antagonist) caused dose-dependent shifts of the dose-response curves of histamine and dimaprit for vasodilatations to the right. Chlorpheniramine did not attenuate the vasodilatations by 2-PEA and histamine. The removal of endothelial cells by an intraluminal injection of saponin (1 mg) did not affect the vascular responses to histamine, 2-PEA and dimaprit. These results indicate that there are 2 types of histamine receptors in canine epicardial coronary arteries: (i) a H1-receptor mediating vasoconstriction and (ii) a H2-receptor, which is not endothelium-dependent, mediating vasodilatation.
Nakane
T
T
Department of Pharmacology, Shinshu University School of Medicine, Matsumoto, Japan.
Chiba
S
S
D000818:Animals; D002744:Chlorpheniramine / Q000494:pharmacology; D002927:Cimetidine / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects* / Q000294:innervation; D017259:Dimaprit; D004285:Dogs; D004730:Endothelium, Vascular / Q000502:physiology; D005260:Female; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D011725:Pyridines / Q000494:pharmacology; D011968:Receptors, Histamine / Q000145:classification / Q000187:drug effects*; D012503:Saponins / Q000494:pharmacology; D013890:Thiourea / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
D011725:Pyridines; D011968:Receptors, Histamine; D012503:Saponins; D002744:Chlorpheniramine; D002927:Cimetidine; D006632:Histamine; C006183:2-(2-aminoethyl)pyridine; D013890:Thiourea; D017259:Dimaprit