Differences in α1-Adrenoceptor Subtype-Mediated Vasoconstriction by Tyramine and Nerve Stimulation in Canine Splenic Artery

Journal of Pharmacological Sciences

Shigetoshi Chiba¹  Xiao-Ping Yang¹ 

[1] Department of Molecular Pharmacology, Shinshu University School of Medicine

关键词: α1A-adrenoceptor;    tyramine;    splenic artery;    canine;    vascular neuroeffector transmission;   

DOI  :  10.1254/jphs.FPJ04057X

学科分类：药学

来源: Nihon Yakuri Gakkai Henshuubu / Japanese Pharmacological Society

【 摘 要 】

References(30)This study was designed to clarify the α1-adrenoceptor subtypes mediating the vasoconstrictor response to tyramine in isolated and perfused canine splenic artery. It was shown that tyramine potentiated the nerve stimulation-induced second peaked vasoconstriction that was readily suppressed by prazosin treatment. A bolus injection of tyramine (0.01 - 0.3 μmol) caused a vasoconstriction in a dose-related manner. The tyramine-induced vasoconstriction was inhibited by WB 4101 (10 and 100 nM), an α1A-and α1D-adrenoceptor antagonist, in a concentration-related manner. Neither BMY 7378 (100 nM), a selective α1D-adrenoceptor antagonist, nor chloroethylclonidine (60 μM), an α1B- and α1D-adrenoceptor antagonist, affected the tyramine-induced response. The results indicate that the noradrenaline released by tyramine may diffuse to the extrajunctional cleft, and thus it activates the extrajunctional α1A-adrenoceptors, because nerve stimulation-evoked second peaked vasoconstrictions were markedly inhibited by chloroethylclonidine but not by WB 4101.

【 授权许可】

Unknown