Figure 3.

Neuronal properties carried only by transfected wild-type or mutant Na_v1.6 channels. Hippocampal neurons transfected with wild-type or mutant Na_v1.6 channels were recorded in the presence of tetrodotoxin to block endogenous Na⁺ channels. (A) Representative voltage traces of evoked action potentials (APs) from neurons transfected with wild-type (black) or mutant channels (colour code in the bottom left). (B) Numbers of evoked action potentials plotted versus injected current in the presence of tetrodotoxin. Shown are means ± SEM. (C) Area under the curve for the input-output relationships. (D) Peak Na⁺ current amplitudes of neurons transfected with wild-type or mutant Na_v1.6 channels in the presence of tetrodotoxin. Rheobase (E) and threshold (F) were significantly decreased in neurons transfected with p.(Phe846Ser) or p.(Leu840Pro) variants compared with the wild-type channels. The p.(Asn1877Ser) variant also significantly decreased the rheobase. The rheobase or threshold could not be obtained in neurons transfected with p.(Asn374Lys), p.(Val1758Ala), p.(Thr1787Pro) and p.(Ile 1654Asn) mutant channels due to very few evoked action potentials. Box-and-whisker plots (C–F) show means (plus symbol), the 25th, 50th and 75th percentiles, minima and maxima; *P < 0.05; **P < 0.01; ***P < 0.001; one-way ANOVA with Dunnett’s post hoc test or ANOVA on ranks with Dunn’s post hoc test were performed. The numbers of recorded cells and statistical analysis are provided in Supplementary Table 4.