The receptor mechanisms for histamine actions in proximal portion differ from those in distal portion in human coronary artery.
While most distal human coronary arteries markedly relaxed in response to histamine, nearly half the proximal ones contracted only. Thus, we investigated the receptor mechanisms for those heterogeneous histamine actions. After a combination of cimetidine-treatment and endothelial removal, but neither one alone, proximal and distal rings contracted to histamine to the same degree. It is suggested that histamine hypercontractility in proximal human coronary artery is due to a lack of both direct (H2-receptor) and endothelial-mediated (H1-receptor) relaxant actions.
Keitoku
M
M
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai.
Maruyama
Y
Y
Takishima
T
T
D002927:Cimetidine / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects* / Q000378:metabolism; D006632:Histamine / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D011969:Receptors, Histamine H1 / Q000378:metabolism; D011970:Receptors, Histamine H2 / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D002927:Cimetidine; D006632:Histamine