Partial Block by Riluzole of Muscle Sodium Channels in Myotubes from Amyotrophic Lateral Sclerosis Patients

Figure 1

Effect of riluzole on voltage-gated sodium currents. (a) Family of currents evoked by test pulses from −65 mV to +60 mV in 5 mV increments (top traces), from a steady holding potential of −80 mV, under control conditions or in the presence of riluzole (1 μM, 30 s pretreatment). Peak current-voltage plot was constructed for the same recordings. (b) Activation curves obtained in the absence or presence of riluzole, with the best fitting Boltzmann curves (black lines). Riluzole induced a depolarizing shift of the curve of about 3 mV and was slightly but significantly increased. (c) Typical currents evoked by fast inactivation two-pulse protocol (top traces): a prepulse (20 ms) from −140 mV to −15 mV in 5 mV increments followed by a test pulse to −10 mV. Holding potential between recordings was −80 mV. (d) Steady-state fast inactivation curves had a hyperpolarizing shift, accompanied by a decrease of . Symbols as indicated.

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