Distinct effects of Cu²⁺ and Zn²⁺ on kinetics of Ca_v2.3 currents. (A and B) Representative current recordings obtained in response to a depolarizing pulse to +10 mV (V_hold = −90 mV) in HEPES, Tricine, and Cu²⁺- or Zn²⁺-containing extracellular solutions. (C) Normalized and averaged current recordings (n = 5).