Figure 8.

The effect of riluzole on transient Na⁺ currents evoked by a 50 ms pulse to -20 mV in a preBötC region neuron is dependent on holding potential. A-D, Representative Na⁺ currents evoked in control and with riluzole (3 μm) by a step from holding potentials of -100 (A), -80 (B), -60 (C), and -55 (D) mV. Insets, Currents at the end of 50 ms steps at higher resolution. Note the enhanced effect of riluzole on transient and persistent Na⁺ currents with steps initiated from depolarized holding potentials. E, Summary of the reduction of transient (□) and persistent (▪) Na⁺ current by riluzole (3 μm; n = 11). F, Riluzole reduced the inactivation time course at potentials more negative than -30 mV. Currents were evoked by 50 ms step depolarizations from -45 to 0 mV (5 mV increments) from a holding potential of -80 mV. Decaying phases of current traces were fit by a monoexponential function, and the time constant in the absence (○) and presence (•) of riluzole was plotted as a function of the test potentials. RIL, Riluzole; CTRL, control.