Figure 3.

Sodium currents elicited by a family of 10-ms lasting depolarizations from a −140 mV holding potential to voltages ranging from −90 to +20 mV in 5-mV steps were recorded from tsA-201 cells expressing WT, Arg-672→His, and Arg-672→Gly α subunit channels. The maximum peaks were normalized to identical amplitudes. (B) Corresponding peak current-voltage relationships (n = 5–7) normalized to maximum (=100%). (C) Voltage dependence of the activation time constants is plotted against voltage steps. The kinetics of activation were estimated by determining the rise time between 10% and 90% (n = 5–9). (D) Deactivation kinetics measured at 15°C. Cells held at −140 mV were depolarized for 500 μs to +20 mV before stepping back to test potentials shown (n = 3–5).