Figure 8.

The Po at limiting [Ca²⁺]_i at 0 mV is significantly lower in hSlo-D292N than in hSlo. (A) Single channel activity from inside out patches of oocytes expressing hSlo (left) and hSlo-D292N (right) channels. Recordings at 0 mV, in asymmetric K⁺ concentration ([K⁺]_o = 5 mM, [K⁺]_i = 120 mM) with 400 μM free [Ca²⁺]_i. (B) Total point histograms from the experiment in A. (C) Po vs. [Ca²⁺]_i plot at 0 mV for hSlo and hSlo-D292N. Each point is the average of three patches of hSlo channels and six membrane patches for hSlo-D292N channels. The data were fitted to the Hill equation (Po = MaxPo/(1+(K_1/2/[Ca])ⁿ)), with n = 1.3, MaxPo = 0.06 D292N, and n = 1.7, MaxPo = 0.47 for WT. K_1/2 = 19.5 μM for both channels.