Differences in the kinetics between WT and mutant sodium channels.
(A) Sodium currents of WT and mutant Na+
channels. Currents were induced by a step depolarization to 0 mV from a
holding potential of −120 mV. (B) Enlargement of the
area within dashed line in A. Peak amplitudes were 5.2
nA for WT, 3.9 nA for R524Q, 4.4 nA for R187W, and 4.1 nA for R19K. The
peak currents were normalized. (C) Time constant of the
decay during a step depolarization. Current decay was fitted by a
single exponential function. The decay time constant was significantly
slower in R187W channels than in WT, R19K, or R524Q channels. Each
point is given as mean ± SEM (n = 7).
Statistical test was done by ANOVA. **, the statistical
difference at 1% level.