Endothelium-dependent relaxation in response to low concentrations of bradykinin is enhanced by phosphoramidon, bosentan and BQ-123 in bovine coronary arteries in vitro.
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.
Ishiguro
S
S
Department of Veterinary Pharmacology, Faculty of Agriculture, Kagoshima University, Japan.
Nakamura
Y
Y
Kawase
J
J
Miyamoto
A
A
Nishio
A
A
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000959:Antihypertensive Agents / Q000494:pharmacology*; D000077300:Bosentan; D001920:Bradykinin / Q000494:pharmacology*; D002417:Cattle; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D006020:Glycopeptides / Q000494:pharmacology*; D009924:Organ Culture Techniques; D010456:Peptides, Cyclic / Q000494:pharmacology; D017466:Receptors, Endothelin / Q000502:physiology; D013449:Sulfonamides / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D000900:Anti-Bacterial Agents; D000959:Antihypertensive Agents; D006020:Glycopeptides; D010456:Peptides, Cyclic; D017466:Receptors, Endothelin; D013449:Sulfonamides; D000077300:Bosentan; C072247:cyclo(Trp-Asp-Pro-Val-Leu); D001920:Bradykinin; C008890:phosphoramidon