A study on Na+ -coupled oxidative phosphorylation: ATP formation supported by artificially imposed delta pNa and delta pK in Vibrio alginolyticus cells.

Addition of Na+ to the K+-loaded Vibrio alginolyticus cells, creating a 250-fold Na+ gradient, is shown to induce a transient increase in the intracellular ATP concentration, which is abolished by the Na+/H+ antiporter, monensin. The delta pNa-supported ATP synthesis requires an additional driving force supplied by endogenous respiration or, alternatively, by a K+ gradient (high [K+] inside). In the former case, ATP formation is resistant to the protonophorous uncoupler. Dicyclohexylcarbodiimide and diethylstilbestrol, but not vanadate, completely inhibit Na+ pulse-induced ATP formation. The data agree with the assumption that Na+ -ATP-synthase is involved in oxidative phosphorylation in V alginolyticus. Interrelation of H+ and Na+ cycles in bacteria is discussed.