Figure 4.

Spiperone increases intracellular Ca²⁺ concentration by inducing a PLC-dependent Ca²⁺ release from the ER. [Ca²⁺]_cyt (upper panel) and [Ca²⁺]_ER (lower panel) were simultaneously evaluated before and after spiperone exposure. Graphs representing the mean of fluorescence kinetics over time with (black line) or without extracellular Ca²⁺ (grey line) in HCT116 (a) and CRC-SC#1 (b) cells. Histogram displaying quantification of fluorescence peaks relative to basal signal for Indo-1 AM and Mag-Fluo-4 AM in HCT116 and CRC-SC#1 (c) cells. Evaluation of the effects of U73122 and 2-APB on spiperone-induced intracellular Ca²⁺ modulation, [Ca²⁺]_cyt (upper panel), and [Ca²⁺]_ER (lower panel) were simultaneously evaluated in the absence of extracellular Ca²⁺ before and after spiperone exposure. Graph representing the mean of fluorescence kinetics over time in cells pretreated with vehicle (dotted black line), U73122 10 μmol/L (solid black line), and 2APB 50 μmol/L (solid grey line) in HCT116 cells (d) and CRC-SC#1 cells (e). Histogram displaying quantification of fluorescence peaks relative to basal signal for Indo-1 AM and Mag-Fluo-4 AM in HCT116 cells and CRC-SC line #1 (f). Data represent the mean ± SD of at least three independent experiments. *: Student’s t-test p < 0.05; **: Student’s t-test p < 0.01; ***: Student’s t-test p < 0.001; ****: Student’s t-test p < 0.0001.