Fig. 1. Inhibition of Na^v1.4 by equipotent concentrations of various inhaled anesthetics. Na⁺currents (  I^Na ) were recorded from a holding potential of –80 mV by 25-ms test steps to V^max(–10 or –20 mV) as shown in the  inset . The effects of halothane (  A , 0.40 mm; 1.1 minimum alveolar concentration [  MAC ]), isoflurane (  B , 0.42 mm; 1.2 MAC), and sevoflurane (  C , 0.46 mm; 1.0 MAC), enflurane (  D  , 0.81 mm; 1.1 MAC), and desflurane (  E , 0.85 mm; 1.1 MAC) at ∼1 MAC are shown in these representative traces (summary data are given in Results). The time-course of  I ^Nainhibition expressed as fractional  I ^Na(  I ^Na /I ^Nacontrol) during application of isoflurane (0.43 mm, 1.2 MAC) or halothane (0.39 mm, 1.1 MAC) for 1.5 min is shown in  F . I ^Nawas repetitively activated from a holding potential of –120 mV by 25-ms test pulses to –10 mV at 0.5-s intervals.