Figure 3. I_Cl,IR is blocked by Cd²⁺ and Zn²⁺.

A, currents evoked by the same voltage protocol as Fig. 1A were obtained in control solution, in the presence of 10 μM Cd²⁺ and after wash. B, 300 μM Zn²⁺ completely and reversibly inhibits currents evoked by the same voltage protocol as Fig. 2B. Current traces a-d were recorded at the time points indicated. Internal solution contained 10 mM BAPTA and cell dialysis of 15 min had occurred before the data were recorded. C, concentration-response curve for inhibition by Zn²⁺ at -90 mV. Data for concentrations between 1 and 1000 μM (means ±s.e.m.; n=3 or 4 for each point) are fitted by the Hill equation with slope constrained to 1, giving an IC₅₀ of 23 μM.