Fig. 7. Effects of sevoflurane and dofetilide on action potentials recorded from guinea pig myocytes. (  A ) Action potential waveforms illustrating the effects of sevoflurane (0.5 mm) alone, dofetilide (10 nm) alone, and the combination of the two drugs. (  B ) Summary of the action potential duration at 50% repolarization (APD⁵⁰) after various treatment conditions.  Error bars indicate SEM (n = 6). (  C ) Summary of the action potential duration at 90% repolarization (APD⁹⁰) after various treatment conditions. * Significantly different from control (  P < 0.05).  Error bars indicate SEM. For  B and  C , the data are expressed as the percent increase over the control (pretreatment) value.