Figure 5. Ca²⁺- and voltage dependence of Ca²⁺-activated Cl⁻ channels in inside-out patches.

A, total single channel open probability (NP_o) at +100 and −100 mV for values of [Ca²⁺]_i between 10 nm and 1 µm. B, plot of NP_ovs.[Ca²⁺]_i at patch potentials between +100 mV and −100 mV. Data at each voltage were fitted by the Hill equation to give the apparent dissociation constant (K_d) and the Hill coefficient (n_H). C, K_d values obtained from B plotted against patch potential. D, plot of n_H values from B vs. patch potential. The data points in both C and D were fitted by a straight line. Data are presented as the means ± s.e.m., n = 4-10. *P < 0.05, **P < 0.01 and ***P < 0.001; unpaired t test.