Fig. 3

Gating properties of hNaV1.4/WT and hNaV1.4/E452K. (A) Voltage-dependence of steady-state activation and inactivation of hNaV1.4/WT (activation, n = 15; inactivation, n = 8) and hNaV1.4/E452K (activation, n = 16; inactivation, n = 9). The activation curves were obtained from I/V relationships, while the inactivation curves were derived using the protocol shown in the insets. The resulting data were fitted to a standard Boltzmann distribution. The slope factor k activation for hNav1.4/E452K was significantly greater than for hNav1.4/WT (**p < 0.01). (B) The predicted window current was obtained using the following equation: (1/(1 + exp ((V0.5activation—V)/k activation)) x ((1—C)/(1 + exp ((V -V0.5inactivation)/kinactivation)) + C) × 100. The open probability was 2.2 times higher in hNav1.4/E452K than in hNav1.4/WT. (C) Time courses of recovery from inactivation in hNaV1.4/WT (n = 7) and hNaV1.4/E452K (n = 8).