Figure 4. Normalized conductance-voltage relationships in external solutions containing 65 (A) or 130 mm (B) sodium before (filled symbols) and after (open symbols) channel modification by 100 μm AC.

Conductance (g_m) measurement and subsequent fit with an empirical Boltzmann function are described in Methods. A, normalized membrane conductance of hH1 (▪, □) and μ1 (•, ○) channels in 65 mm external sodium solution. B, normalized membrane conductance in 130 mm external sodium solution. Data in A and B are from the same cells used to plot the current-voltage relationships in Fig. 3. The midpoint voltages (V_0.5), slope factors (k) of the fitted Boltzmann function, and number of cells (n) for each data set are listed in Table 1.