Effects of TPC2 agonists on cytosolic Ca ²⁺ in human dopaminergic neurons. (a and b) Summary data (mean ± SEM from three to four independent biological replicates) quantifying the peak change in the Ca²⁺ signals in two PD lines in response to TPC2-A1-N (30 µM), TPC2-A1-P (30 µM), or a combination of the two. Each point represents the mean response from an independent cell population (a) or single cell (b) separated by line. (c and d) Summary data quantifying the peak change in the Ca²⁺ signals in two healthy control lines in response to 50 mM K⁺. Each point represents the mean response from an independent cell population (c) or a single cell (d) separated by line. (e and f) Summary data quantifying the peak change in the Ca²⁺ signals in 3 PD lines in response to 50 mM K⁺ treated with TPC2-A1-P (30 µM) or vehicle (DMSO) prior to stimulation. Each point represents the mean response from an independent cell population or a single cell separated by line (e and f) and upon combination (g and h). *P < 0.05 (unpaired t test).