Relaxant effects of propofol on human omental arteries and veins.

We have investigated the relaxant effects of propofol on smooth muscle tension in human omental arteries and veins to determine if endothelium-related mechanisms are involved. Isolated vessel segments were precontracted with endothelin-1 and propofol was added cumulatively (10(-7)-10(-4) mol litre-1). In both artery and vein segments, propofol induced relaxation, which was not dependent on an intact endothelium. Relaxation was reduced when the extracellular K+ concentration was increased and in the presence of tetraethylammonium chloride (TEA). In intact segments, N-nitro-L-arginine methyl ester (L-NAME), indomethacin, glibenclamide, 4-aminopyridine, clotrimazole and atropine did not affect the concentration-response curve of propofol. This indicates that propofol relaxes human omental arteries and veins in an endothelium independent manner, and that hyperpolarization caused by activation of the K+ channel, BKCa, may be involved.