Endothelium-dependent relaxation in response to low concentrations of bradykinin is enhanced by phosphoramidon, bosentan and BQ-123 in bovine coronary arteries in vitro. |
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Authors: | S Ishiguro Y Nakamura J Kawase A Miyamoto A Nishio |
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Affiliation: | Department of Veterinary Pharmacology, Faculty of Agriculture, Kagoshima University, Japan. |
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Abstract: | An endothelin (ET)-converting enzyme inhibitor phosphoramidon (10 microM), an ET(AB)-receptor antagonist bosentan (10 microM) and an ET(A)-receptor antagonist BQ-123 (1 microM) 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 microM), an ET(B)-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 ET(A)-receptor antagonism. |
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