Fig. 3. Concentration-dependence of effect of propofol on acetylcholine-induced maximum relaxation in endothelium-intact strips of rabbit mesenteric artery. Acetylcholine (1 μM) was applied for 2 min during a 10 μM norepinephrine (NE)-induced tonic contraction before (control) and after application of various concentrations of propofol (0.1–10 μM). Propofol at each concentration was pretreated for 15 min and was then present throughout the experiment. Each symbol shows the mean of data from four strips, with SD shown by vertical lines. All tests were carried out in a solution containing 0.1 mM L-NOARG, 5 μM guanethidine, 0.3 μM nicardipine, and 3 μM propranolol. *Significant difference from control (  P < 0.05).