Participation of H1-Receptors in Histamine-Induced Contraction and Relaxation of Horse Coronary Artery In Vitro

Journal of Veterinary Medical Science

Mitsuharu MATUMOTO¹  Akira NISHIO¹  Atsushi MIYAMOTO¹  Takeshi OBI¹  Shigeru ISHIGURO¹ 

关键词: coronary artery;    endothelium-dependent relaxation;    H1-receptor;   

DOI  :  10.1292/jvms.53.789

学科分类：兽医学

来源: Japanese Society of Veterinary Science

【 摘 要 】

References(18)Cited-By(8)The mechanisms of histamine-induced contraction and relaxation were investigated in rings isolated from a middle part of the left descending coronary arteries of horses. Intact and endothelium-denuded preparations were compared. Rings of horse coronary arteries contracted in response to histamine in a concentration dependent manner, but some of them relaxed with lower concentrations and contracted with higher concentrations. Removal of the endothelium abolished the relaxation and potentiated the contraction. The pD2 values were 4.70±0.08 in the rings with intact endothelium and 4.95±0.08 in endothelium-denuded rings. Histamine-induced contractions in intact and denuded preparations were not affected by an H2-antagonist, cimetidine, but were inhibited by an H1-antagonist, diphenhydramine in non-competitive manner in the rings with endothelium and in competitive manner in denuded rings. After precontraction with PGFSUP2α or norepinephrine, histamine relaxed preparations with intact endothelium (pD2 value, 7.80±0.11), although histamine-induced relaxations were not observed in denuded preparations. The relaxation was competitively inhibited by diphenhydramine. Relaxing response was significantly attenuated by methylene blue, quinacrine, L-nitro-arginine, gossypol and AA861 but not by indomethacin. These results suggest that the hisidmine-induced contraction and relaxation in horse coronary arteries are mediated mainly by H1-receptors in the smooth muscle and endothelium, respectively, and H1-receptor activation of endothelial cells may liberate vasodilator substance(s).

【 授权许可】

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