| Abstract: | Rat liver mitochondria are not fully functional at birth. The relationship between this deficiency and the affinity for phosphate, in oxidative phosphorylation or in phosphate transport, have been studied.The phosphate concentration necessary to observe maximal rate of succinate oxidation in the presence of ADP was higher for newborn than for adult rat liver mitochondria. After preincubation of newborn rat liver mitochondria with ATP, the rate of succinate oxidation in the presence of ADP increased with phosphate concentration similarly for newborn and adult rat liver mitochondria. The maximal rate of phosphate-acetate exchange, which is an indirect measure of the rate of phosphate transport across the mitochondrial membrane, was not significantly different for adult and newborn rat liver mitochondria. On the contrary the apparent affinity for phosphate was about ten-fold lower for newborn than for adult mitochondria. |
