Kinetics of Zn²⁺-induced modulation at different holding potentials. (A) Time course of Zn²⁺-induced changes in peak currents carried by 4 mM free Ca²⁺ and evoked by voltage steps to 10 mV from the indicated holding potentials (n = 6–9 cells per holding potential). (B) Time course of Zn²⁺-induced changes in activation time constants determined in the same cells as in A. (C) Mean current traces recorded at the indicated time points before, during, and after Zn²⁺-application from a holding-potential of −60 mV (n = 8 cells). (D) Mean current traces recorded as in B but from a holding potential of −90 mV (n = 8 cells).