Fig. 1. Effects of etomidate (A  and B ) and ketamine (C  and D ) on the endothelium-dependent relaxation induced by acetylcholine in pulmonary arteries. Arterial rings were precontracted to the ED⁵⁰level of tension with phenylephrine. Relaxation responses are expressed as the percentage of phenylephrine precontraction. Etomidate (10⁻⁵m) had little effect (A ), whereas etomidate (10⁻⁴m) significantly attenuated (* P < 0.05) the relaxation induced by acetylcholine (B ). Ketamine also inhibited (* P < 0.05) acetylcholine-induced relaxation at a concentration of 10⁻⁴m (D ) but not at 10⁻⁵m (C ).