Fig. 2. Concentration-response curves to levcromakalim in the absence or in the presence of ketamine racemate (10⁻⁵, 3 × 10⁻⁵, 10^{− 4}m), obtained in the rat thoracic aorta with or without endothelium. Data are shown as means ± SD and expressed as percent of maximal relaxation induced by papaverine (3 × 10⁻⁴m; 100%= 1,160 ± 221 mg [n = 5], 1,032 ± 267 mg [n = 5], 976 ± 54 mg [n = 5], and 1,008 ± 270 mg [n = 5], for control rings with endothelium and rings treated with ketamine racemate [ 10⁻⁵, 3 × 10^{− 5}, or 10⁻⁴m], 100%= 1,060 ± 86 mg [n = 5], 936 ± 43 mg [n = 5], 956 ± 120 mg [n = 5], and 944 ± 100 mg [n = 5], for control rings without endothelium and rings treated with ketamine racemate [ 10⁻⁵, 3 × 10^{− 5}, or 10⁻⁴m], respectively). *Difference between control rings and rings treated with ketamine racemate (3 × 10⁻⁵, 10⁻⁴m) is statistically significant (P < 0.05).