[Effect of protein inhibitors of mitochondrial ATPase in intact rat thymocytes and Ehrlich ascites carcinoma cells].

It has been found that inhibition of mitochondrial ATPase in living thymocytes and Ehrlich ascites carcinoma (EAC) cells after incubation of cells with uncoupler, rotenone or cumene hydroperoxide, depends, in a large measure, on the inhibitor protein (IF1) action. Maximum inhibition (up to 70% of the oligomycin-sensitive ATPase activity) was found in the presence of the uncoupler in the incubation medium. Even when IF1 action was maximum, the residual ATPase activity caused marked ATP depletion in thymocytes, while in EAC cells other ATP-consuming processes prevailed. No inactive ATPase-IF1 complexes were found in intact thymocytes and EAC cells. The extent of inhibition of mitochondrial ATPase under oxidative stress was higher in thymocytes than in EAC cells and depended on cumene hydroperoxide concentration and duration of cell cellular ATP depletion. It is suggested that under certain experimental conditions IF1 can prevent cell death by slowing down the hydrolysis of cellular ATP.