Voltage-dependent dissociation of CPA from the pore. (A) The experiments were performed in excised inside-out patches similar to those shown in Fig. 4, except that the stepping voltages were applied at a fixed time point (40 ms after the rapid solution exchange) and varied from +80 to −160 mV (in −20-mV steps). See inset for the voltage protocol. The small current spike at the beginning of each recording was due to the switch of the membrane voltage from the initial voltage (−160 mV) to V_c. [Cl⁻]_i and [Cl⁻]_o before (left arrow) and after (right arrow) the rapid solution exchange are as indicated (in mM). (B) Time constants of CPA-dissociation processes obtained from experiments like those shown in A (as a function of the stepping voltage [V_m]; open symbols) and those shown in Fig. 4 (as a function of V_c; filled symbols). The recording conditions were as indicated.