Figure 3.

Effects of 100 μM RSD 921 on the voltage-dependence of conductance of heart, skeletal muscle and neuronal Na⁺ channels. Conductance was examined by 12 ms depolarizations from −100 mV (−120 mV for the heart channel) to potentials ranging from −90 to +50 mV in 10 mV increments every 6 s and dividing by (V-V_rev), in which V is the test potential and V_rev is the reversal potential for Na⁺. The reversal potentials were determined as described in the Methods. The data points in all panels were determined from at least five oocytes and error bars represent standard deviations. All curves were fit with a two-state Boltzmann function as described in the Methods, with the parameters of the fits in Table 2. Conductance curves are shown in the absence and presence of 100 μM RSD 921. The data for 100 μM RSD 921 are scaled to the maximum to demonstrate the shifts in the voltage-dependence of conductance.