Relation between extra- and intramitochondrial ATP/ADP ratios in rat liver mitochondria.

Changes of the extra- and intramitochondrial ATP/ADP ratios as a function of the respiratory state were measured in incubations with rat liver mitochondria. ATPase or creatine/creatine kinase was used to change the extramitochondrial ATP/ADP ratio; the separation of the mitochondrial pellet was performed by a Millipore filtration technique. Under all conditions tested, the intramitochondrial ratio changed in the same direction as the extramitochondrial one, except in the presence of atractylate where this correlation was not observed. Furthermore, it could be shown that the oxygen uptake and pyruvate carboxylase activity correlated with the intramitochondrial ATP/ADP ratio and not with the extramitochondrial one. These results do not support the proposal that the adenine nucleotide translocase is rate limiting for respiration.