Fig. 2
Patch-clamp recordings in HEK293T cells expressing recombinant Nav1.2 wild-type or mutant channels. Variants E1803G (blue) and L1342P (green) have been detected in patients with EE, L1563V (red) in a family with BFNIE, and R937C (purple), L611Vfs*35 (orange) and W1716* (light blue) cause ID. a Family of whole-cell sodium currents of wild-type and conducting mutant Nav1.2. b Peak current amplitudes normalized to cell capacitance (bars are mean ± SEM) were not significantly different. c Voltage dependence of activation obtained by plotting the normalized conductance against test potentials and fitted with a Boltzmann function. L1342P showed a significant negative shift (p < 0.001). d Voltage dependence of steady-state inactivation obtained by displaying the normalized current amplitude against the prepulse potential fitted with a Boltzmann function. A negative shift was observed for both L1342P (p < 0.001) and L1563 V (p = 0.017), while E1803G had a shallower slope (p < 0.001). e Activation and inactivation curves of L1342P in comparison to wild-type demonstrating a hyperpolarized shift with unchanged activation-inactivation coupling. f Activation and inactivation curves of E1803G in comparison to wild-type illustrating the increase of the window current. g Time-dependent recovery from inactivation fitted with a single exponential function and plotted against a logarithmic time scale. A significantly slower recovery rate was observed in L1342P (p = 0.002). h Use-dependent inactivation. The frequencies of depolarizing pulse trains are plotted against the residual peak current amplitude of the last pulse normalized to the peak current amplitude of the first pulse. i 10–90% rise time depicted against test potentials. L1342P exhibited a significantly faster rise time at the voltage step to − 30 mV (p = 0.02). k Fast inactivation time constants plotted against test potentials