FIGURE 5.

Glycolytic inhibitors, but not mitochondrial inhibitors, inhibit PMCA activity and store-operated Ca²⁺ entry in MIA PaCa-2 cells. A–E, representative traces show the in situ [Ca²⁺]_i clearance assay (PMCA activity) in fura-2-loaded MIA PaCa-2 cells. CPA (30 μm) was applied in zero external Ca²⁺ with 1 mm EGTA (white box) or 20 mm Ca²⁺ (gray box) to induce store-operated Ca²⁺ influx. Subsequent removal of external Ca²⁺ resulted in [Ca²⁺]_i clearance. This influx-clearance phase was repeated using a paired experimental design, and metabolic inhibitors were applied during this second influx-clearance phase. The inset of each trace shows expanded time courses comparing the second (gray trace) with the first clearance phase (black trace) in the presence of each metabolic inhibitor. A, TMC; B, 2 mm IAA; C, 10 μm OM; D, 500 μm BrPy; E, 4 μm CCCP. Linear clearance rate over 60 s during the second clearance phase was normalized to that of the first (% relative clearance). F, normalized linear rate (± S.E.). **, p < 0.01; ***, p < 0.001 (Mann-Whitney U test), compared with TMC.