Jpn. J. Pharmacol. 73 (1), 101-103 (1997)

beta1-Adrenoceptor-Mediated Relaxation by Norepinephrine in Dog Hepatic Arteries

Susumu Shiraishi, Tomio Okamura and Noboru Toda (*)

Department of Pharmacology, Shiga University of Medical Sciences, Seta, Ohtsu 520-21, Japan
(*) To whom correspondence should be addressed.

Abstract: Dog hepatic arterial strips treated with prazosin responded to norepinephrine with concentration-related, endothelium-independent relaxations, the maximal response being 81.7% of the papaverine-induced maximal relaxation that was markedly greater than that in renal arteries. The norepinephrine-induced relaxation in hepatic arteries was significantly attenuated by metoprolol but not influenced by butoxamine. Relaxant responses to norepinephrine of dog hepatic arteries appear to be mediated by the beta1-adrenoceptor subtype, like those of coronary arteries. Evidence for functioning of the beta1-subtype in hepatic arteries would contribute to the analysis of neural and hormonal regulation of blood flow in the liver.

Keywords: Hepatic artery, Norepinephrine, beta1-Adrenoceptor