Fig. 2. Concentration dependence of current inhibition. (A ) Sample data before and after 0.7%, 1.5%, and 3% halothane treatment. Currents shown were obtained pulsing to −10 mV and then to −40 mV. For comparison, all traces were normalized to the control at 1.5% halothane. (B ) The plot shows the average current block by 0.7%, 1.5%, and 3% halothane as a function of test potential. For depolarizations between −40 mV to +40 mV, the average block was 14.0 ± 1.4%, 21.7 ± 1.9%, and 34.5 ± 2.0% for 0.7%, 1.5%, and 3% halothane, respectively. (C ) Average tail current block at −40 mV after treatment with 0.7%, 1.5%, and 3% halothane as a function of the depolarizing test potential. The average block within the range −40 mV to 40 mV was 10.3 ± 1.1%, 20.6 ± 1.4%, and 31.7 ± 0.4% with 0.7%, 1.5%, and 3% halothane.