Jpn. J. Pharmacol. 86 (2), 262-264 (2001)


Endothelium-Dependent Relaxation in Response to Low Concentrations of Bradykinin Is Enhanced by Phosphoramidon, Bosentan and BQ-123 in Bovine Coronary Arteries In Vitro

Shigeru Ishiguro, Yutaka Nakamura, June Kawase, Atsushi Miyamoto and Akira Nishio*

Department of Veterinary Pharmacology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan

*Corresponding author. FAX: +81-99-285-8717, E-mail: nishio@vet.agri.kagoshima-u.ac.jp


Abstract: An endothelin (ET)-converting enzyme inhibitor phosphoramidon (10 mM), an ETAB-receptor antagonist bosentan (10 mM) and an ETA-receptor antagonist BQ-123 (1 mM) potentiated endothelium-dependent relaxation of bovine coronary arteries in response to bradykinin (BK) at femtomolar to picomolar concentrations, but not at nanomolar concentrations. BQ-788 (3 mM), an ETB-receptor antagonist, showed no significant effects on fM - nM BK-induced relaxation. These results suggest that the endothelium-dependent relaxation of isolated bovine coronary arteries induced by very low concentrations of BK is partly regulated by a complex mechanism involving the ETA-receptor antagonism.

Keywords: Bradykinin, Endothelin, Endothelium-dependent relaxation
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