Fig. 4. Relations between anesthetic potencies (minimum alveolar concentration [MAC]) and Ca2+-activated K+channel current (IK(Ca)) (A ) and delayed rectifier K+channel current (IK(DR)) (B ) at +60 mV, expressed as a percentage of the control, in tracheal and bronchial smooth muscle cells. Data are expressed as mean ± SD (n = 7). *P < 0.05 versus 0 MAC anesthetic; †P < 0.05 versus IK(Ca)at the same anesthetic potencies.