Fig. 1. Mitochondrial depolarization reduces the rate of Ca²⁺ entry in intact cells. After depleting stores with thapsigargin in Fura 2-loaded cells, readmission of external Ca²⁺ (2 mM) resulted in a rapid increase in cytosolic Ca²⁺ concentration (control). This was substantially reduced by depolarizing mitochondria with either 5 µM FCCP (A) or antimycin A (5 µg/ml) plus oligomycin (0.5 µg/ml) (B). The differentiated signals are shown in (C) and (D). (E) Bar chart comparing the initial slope of the Ca²⁺ signal upon Ca²⁺ readmission in control cells with those pre-exposed to either FCCP or antimycin A plus oligomycin. Numbers of cells (n) for each condition are: control (ctrl) 40, FCCP 38, antimycin A plus oligomycin (Anti A/Oligo) 35. (F) Bar chart plotting the peak rate of Ca²⁺ increase (obtained from the differentiated signal) for the conditions shown. *p < 0.01.