A–C) I-V relation of ICa in external solutions containing 145mM (◇) and 10 mM (▽) NaCl using 140 mM of LiCl, CsCl or TEACl to replace the remaining NaCl. D) Representative traces of ICa suppression in 10 mM Na+ replacing the extracellular cation with Li+, Cs+ and TEA+. E) Quantitative representation of relative peak current suppression from baseline when extracellular monovalents were varied between Na+, Li+, Cs+ and TEA+ in 10 mM Na+ (N=6–15, p<0.01 for all three conditions).