Figure 3.

Ca²⁺ entry and intracellular Ca²⁺ facilitate somatodendritic DA release. a, Average [DA]_o versus time profiles evoked by local stimulation (30 pulses, 10 Hz) in the SNc in the absence and presence of a nonselective Ca²⁺ channel blocker, Cd²⁺ (100 μm, n = 6). b, Average [DA]_o versus time profiles in SNc in the absence and presence of a fast-acting Ca²⁺ chelator BAPTA-AM (BAPTA) (50 μm, n = 6). c, Summary of the effect of Cd²⁺ and BAPTA on peak [DA]_o; evoked [DA]_o was measured at the time point of control peak [DA]_o, which was taken as 100%. Blockade of stimulus-induced Ca²⁺ entry by Cd²⁺ abolished evoked [DA]_o (n = 6, ***p < 0.001 vs control), confirming that Ca²⁺ entry is required to trigger evoked somatodendritic DA release. Buffering of stimulus-induced intracellular Ca²⁺ by BAPTA decreased evoked [DA]_o (n = 6, **p < 0.01 vs control), demonstrating the involvement of intracellular Ca²⁺ elevation in evoked somatodendritic DA release.