Fig. 1. Differential modulation of the excitability in SNc dopaminergic neurons by EGTA or BAPTA as internal Ca2+ chelators in the presence of Zn2+. (A, B) Left, voltage responses of a SNc neuron to a depolarizing pulse (100 pA current injection for 1 s) in the absence (Control and Wash) and the presence of Zn2+ (100 μM Zn) were recorded using intracellular solutions with 11 mM EGTA (A) or 11 mM BAPTA (B) in the pipette solution. Right, effect of Zn2+ on the frequency of evoked action potentials. (A: Control, 5.92±0.64 Hz, n=13; Zn, 10.54±1.44 Hz, n=13; Wash, 8.08±1.33 Hz, n=12; p<0.05, one-way ANOVA; B: Control, 6.22±0.80 Hz, n=9; Zn, 4.11±0.87 Hz, n=9; Wash, 3.83±0.54 Hz, n=6; p<0.05, one-way ANOVA; *p<0.05, Dunnett’s post-hoc multiple comparison test for control). (C) Summary of the relative frequency in the presence of Zn2+ (100 μM Zn) and after Zn2+ washout (Wash) in the EGTA-, BAPTA-, and TPEN-loaded condition (100 μM Zn: EGTA, 1.81±0.15, n=13; BAPTA, 0.63±0.07, n=9; TPEN, 1.13±0.13, n=4; p<0.001, one-way ANOVA; Wash: EGTA, 1.43±0.99, n=12; BAPTA, 0.61±0.06, n=6; TPEN, 1.15±0.21, n=4; p<0.05, one-way ANOVA; *p<0.05, ***p<0.001, Tukey’s post-hoc multiple comparison test; ##p<0.01; ###p<0.001, one sample t-test, hypothetical value=1).
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