Published online by Cambridge University Press: 23 December 2004
Summary
Background and objective: Propofol may cause undesirable hypotension due to vasodilation. The underlying mechanisms are not completely understood. We investigated the mechanisms by which propofol relaxes vascular segments.
Methods: We studied the effect of propofol on isolated porcine coronary artery rings precontracted with potassium chloride or prostaglandin F2α.
Results: Propofol, in a concentration-dependent manner, relaxed all segments at concentrations of 5 μg mL−1 and above. This relaxation was unaltered in the presence of Nω-nitro-L-arginine, indomethacin, diltiazem and glibenclamide. Tetraethylammonium chloride, an inhibitor of the BKCa K+ channel (a high conductance Ca2+-sensitive K+ channel), dose-dependently attenuated the vasodilating effect of propofol (P < 0.001).
Conclusions: Our results suggests that the activation of the BKCa channel may contribute to the vasodilating effect of propofol, hereby causing hyperpolarization of the smooth muscle membrane and reduction of smooth muscle tone.