Dependence of Zn²⁺ effects on extracellular Ca²⁺ concentration, pH, and histidine residues. (A–E) Comparison of normalized mean current traces (A and B) and changes in half-activation voltage (V_0.5act; C), activation time constants at 10 mV (τ_act; D), and activation slope factor (k_act; E) produced by application of 5.4 µM free Zn²⁺ under the experimental conditions indicated below (n = 5–8 cells per experimental condition). *, P < 0.05; ***, P < 0.001 (one-way ANOVA with Bonferroni post hoc test). DEPC PT, DEPC pretreatment.