Figure 2

Met136Val mutation potentiates current density in ND7/23 cells. Representative current traces of sodium currents recorded from ND7/23 cells expressing either WT (A) or Met136Val (B) mutant channels. Cells were held at −120 mV and inward sodium currents were elicited by step depolarizations from −80 mV to +20 mV in 5 mV increments every 5 s. (C) Peak current-voltage relationship for WT (n = 15) and Met136Val (n = 14) channels showing significant increase in peak current density of M136V mutant channels. (D) Comparison of voltage-dependent activation and steady-state fast inactivation of WT and Met136Val mutant channels. (E) Comparison of steady-state slow inactivation of WT and Met136Val mutant channels. Cells were held at −120 mV and a series of depolarizing pulses (30 s) from −120 mV to +20 mV in 10 mV increments was applied, followed by 20 ms return to −120 mV and then a 20 ms pulse to −10 mV to elicit a test response. Data represent mean ± SE.