In this study the effect of propofol on isolated bovine coronary artery tone was studied in artery rings precontracted with PGF(2 alpha). Propofol, in concentrations of 10(-6)-10(-5) M did not change vascular smooth muscle tone, but at high concentrations (10(-4)10(-1) M) produced relaxation in rings with intact endothelium. In rings denuded of endothelium or treated with methylene blue, propofol produced relaxation at 10(-3)-10(-1) M concentrations, but there was a significant decrease in relaxation compared to endothelium intact rings. In the presence of a calcium agonist (Bay K 8644; 10(-5) M), propofol produced constriction in rings denuded of endothelium. These results suggest that high concentrations of propofol may hale vasorelaxant effect on bovine coronary artery and that these effects may be due to actions on the endothelium and mediated by calcium channels.