FIG 4.

Depletion of intracellular Ca²⁺ stores disrupts purinergic receptor activity in fibroblasts and NPCs. (A) Fibroblasts were treated with 1 μM thapsigargin and analyzed for baseline intracellular Ca²⁺ levels prior to stimulation (left panel), for the number of responding cells following 10 μM ATP stimulation (middle panel), and for percent Ca²⁺ response above baseline (right panel). (B) NPC-derived neurons and astrocytes were analyzed as described for panel A. (C) Thapsigargin-treated fibroblasts were analyzed for baseline intracellular Ca²⁺ levels prior to stimulation (left panel), for the number of responding cells following 50 μM KCl stimulation (middle panel), and for percent Ca²⁺ response above baseline (right panel). (D) NPC-derived neurons and astrocytes were analyzed as described for panel C. Data are from three biological replicate experiments with 50 (fibroblasts) or 100 (neural) cells analyzed in each replicate. (**, P < 0.01; ***, P < 0.001; ****, P = 0.0001; ns, not significant, as determined by ANOVA or chi-square test).