Figure 7.
Voltage dependence of P open at pHi 6.5, 5.5, and 5.0, for the same patch as in Figs. 2–4, and 6. P open was estimated as g H/(N γ H), where the total number of channels in the patch, N, and γH were estimated from the y-gH plot (Fig. 6). Here only the last 1–2 records at each voltage are included, because earlier points were farther from steady-state. Curves show best-fitting (by nonlinear least squares) Boltzmann functions: P open = P max {1 + exp[−(V − V 1/2)/k]}−1 with midpoints (V 1/2) of −11.2, −26.9, and −42.9 mV, slope factors (k) of 5.7, 7.8, and 8.3 mV, and P max of 0.78, 0.93, and 0.98 at pHi 6.5, 5.5, and 5.0, respectively. ES-2596.