Figure 1. Gating characteristics of hNav1.5-CW mutant channels in stably transfected HEK293 cells. (A) A family of superimposed Na⁺ current traces was evoked by 80-ms pulses to voltages ranging from −100 to +50 mV in 10-mV increments. The inward current evoked by a pulse to −70 mV and the outward currents evoked by pulses to 0 and +50 mV are labeled. (B) Conductance was calculated by an equation, g_m = I_Na/(E_m−E_Na), where I_Na is the peak current, E_m is the test voltage and E_Na is the estimated reversal potential. Normalized g_m values were then plotted against the corresponding voltage (open circles). The plot was fitted with a Boltzmann function. The midpoint voltage (V_0.5) and slope (k) of the function were −41.8 ± 1.4 mV and 10.2 ± 0.6 mV, respectively (n = 8). The holding potential was set at −140 mV.