Effects of Zn²⁺ on the shape of macroscopic Ca²⁺ currents. (A) Mean I-V current traces recorded in response to 25-ms (left) or 400-ms (right) voltage steps to the indicated test potentials in the absence (black) and presence (orange) of 5.4 µM free Zn²⁺ at pH 7.4. They have been scaled to their maximum amplitude to highlight kinetic changes. Scale bars correspond to 10 and 100 ms for short and long voltage steps, respectively. (B) Mean II-V current traces recorded at the indicated test potentials in the absence (black) and presence (orange) of 5.4 µM free Zn²⁺ at pH 7.4. They have been scaled to their maximum amplitude to highlight kinetic changes. Scale bars correspond to 2 ms for the tail current at −60 mV and 10 ms for all other test potentials.