Effects of oxaloacetate and beta-hydroxybutyrate on rat liver mitochondrial calcium flow during starvation

Rat liver mitochondria accumulate calcium from the incubation medium both in the presence of ATP and of succinate with rotenone. Lowering free calcium concentration by means of EGTA leads to a reduction of maximum transport capacity to less than 25% of the total added calcium. Under these conditions addition of oxaloacetate inhibits calcium uptake, an effect which is blocked by equimolar concentrations of beta-hydroxybutyrate. Oxaloacetate and acetoacetate induce an efflux of previously accumulated mitochondrial calcium. These effects appear to be independent of free calcium concentration and of whether the mitochondria were obtained from fed rats or rats fasted for 16 h or 4 days.