INFLUENCE OF PHOSPHORYLATION STATE RATIO ON ENERGY-CONSERVATION IN MITOCHONDRIA TREATED WITH INORGANIC ARSENATE

Exposure of rat liver mitochondria to inorganic arsenate, followed by reisolation and washing to remove the added arsenate, results in uncoupled respiration with succinate when assayed for oxidative phosphorylation in presence of greater than 5 mM phosphate. Coupled respiration with these mitochondria can be obtained by either inclusion of ATP, decreasing the concentration of phosphate to less than 5 mM, or exclusion of any added phosphate. Coupling under these several conditions is ascertained through use of 1 or more established criteria, namely, ADP/O, ATP/O and 45Ca2+/O. The efficiency of coupling with arsenate-treated mitochondria is evidently determined by the conditions of the assay system and can be improved through an increase in the imposed phosphorylaton state ratio.