Intracellular pH regulates the production of different oxygen metabolites in neutrophils: effects of organic acids produced by anaerobic bacteria.

The effects of short chain carboxylic acids (SCCA), namely succinic, butyric, and iso-butyric, on neutrophil metabolic activation were assessed. SCCA induced a significant decrease in O2.- recovery and chemiluminescent response in neutrophils activated with the diacylglycerol analog tetradecanoyl-phorbol-acetate (TPA). SCCA did not alter O2 consumption, H2O2 production, or the calorimetrically determined energy expenditure occurring during the metabolic burst. SCCA also induced a significant acidification of intracellular pH (pHi). These results are consistent with an increased divalent versus univalent O2 reduction performed by the NADPH oxidase at a more acidic intracellular pH.