Relaxant effects of propofol on human omental arteries and veins

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