FIGURE LEGENDS
Fig. 1. Recovery from inactivation in the absence and presence of 100 µM riluzole in WT channels. The RFI protocol is shown in the upper panel. The duration of the hyperpolarizing gap between the two depolarizations is progressively increased. Peak amplitudes of the 2nd pulse-evoked currents are plotted against hyperpolarizing gap duration. Thin black lines – normalized control amplitudes in n = 9 cells, thin red lines – amplitudes in the same 9 cells in the presence of 100 µM riluzole. The effect of riluzole in each cell was normalized to the control in the same cell. Averaging (thick lines) was performed as described in Methods.
Fig. 2. Effect of riluzole perfusion as monitored with the 3PT protocol on WT channels. A The voltage protocol. Blue, red, and green color indicate 1st, 2nd, and 3rd depolarizations, respectively, as in panels D to F.
B Example of sodium currents evoked in a typical WT channel expressing cell by the three depolarizations of the 3PT protocol. Subsequent traces are overlaid on each other. Blue traces show control, dark to light red show successive traces during riluzole application, light gray to black traces show successive traces during washout.
C The same currents after subtraction of capacitive and leakage artifacts.
D Illustration of the first 29 consecutive trains (protocol in the upper panel), and the currents evoked by them (lower panel). Peaks of 1st, 2nd, and 3rd pulse-evoked currents are marked with blue, red, and green circles, respectively. Shaded area indicates the perfusion of 100 μM riluzole.
E Amplitude plots for 7 individual cells. Connecting peak amplitudes of 1st (blue), 2nd (red), or 3rd (green) pulse-evoked currents gives a plot of peak amplitudes throughout the whole experiment. To help compare the extent of inhibition, 1st, 2nd, and 3rd pulse-evoked currents were normalized each to its own control (peak amplitudes recorded during the first train).
F Onset and offset time constants (mean ± SEM) for the amplitude plots of the seven cells shown in panel E. Data from one individual cell (the same as in panels B to D) are shown for illustration. Mono- or bi-exponential functions were fitted to traces after correcting for slow inactivation (see Methods). Dashed lines show exponentials fitted to this particular cell.