Fig. 4.

Effect of mitochondrial Ca²⁺ uptake on activation of phagocytic NADPH oxidase in human B lymphoblasts. Stimulation of phagocytic NADPH oxidase by PMA in the presence of mitochondrial inhibitors. Superoxide production was measured in unstimulated or PMA-stimulated lymphoblasts in the presence of ethanol as a vehicle (Control), inhibitor of mitochondrial complex III AA (10 μM), inhibitor of mitochondrial Ca²⁺ uniporter ruthenium red (RR; 5 μM), chelator of intracellular Ca²⁺ BAPTA-AM (BAPTA, 0.1 mM), or mitochondrial proton ionophore CCCP (10 μM). Inhibition of Ca²⁺ uptake by mitochondria with RR significantly increased activity of phagocytic NADPH oxidase similar to CCCP, while chelation of intracellular Ca²⁺ with BAPTA-AM or depletion of intracellular Ca²⁺ with thapsigargin (TG; 1 μM) reduced O₂^·− production in PMA-treated cells. Results are expressed as mean ± SE; n = 4–6. *P < 0.001 vs. Control. **P <0.05 vs. PMA. +P < 0.01 vs. PMA. #P < 0.001 vs. PMA. $P < 0.05 vs. AA + PMA. ¶P < 0.001 vs. PMA. §P < 0.01 vs. CCCP + PMA.