Effect of ATP on the gating of hClC-1. (A) macroscopic current recordings from an inside-out patch upon perfusion with control internal solution (left), during application of 10 mM ATP (middle), and after washout (right). (B) Voltage dependence of the overall open probability obtained from the macroscopic currents in A as described in Materials and methods. Symbols are: square, control; circle, 10 mM ATP; triangle, wash. Lines are fits of Eq. 1 with the following parameters: control, V_1/2 = −89 mV, P_min = 0.14; 10 mM ATP, V_1/2 = −88 mV, P_min = 0.13; wash V_1/2 = −87 mV, P_min = 0.14. (C) Effect of ATP on the slow gating mechanism of hClC-1. Data are from the same patch and were obtained from tail currents preceded by a 200-μs pulse to 160 mV. Symbols are as in B. Lines are fits of Eq. 1 with the following parameters: control, V_1/2 = −82 mV, P_min = 0.59; 10 mM ATP, V_1/2 = −81 mV, P_min = 0.58; wash V_1/2 = −78 mV, P_min = 0.63.