Effects of various ketogenic substrates on gluconeogenesis from lactate or alanine were compared. The results suggest that, in intact liver cells, cytoplasmic pyruvate is transported into mitochondria in exchange for intramitochondrially generated acetoacetate. An interrelationship between gluconeogenesis and ketogenesis may thus exist in the liver at the level of mitochondrial pyruvate carrier.

Effeects of various ketogenic substrates on gluconeogenesis from lactate were examined. D,L-3-Hydroxybutyrate (5 mM) stimulated gluconeogenesis by 41%, the effect being the same as that of 5 mM acetate (49%). No stimulating effect of acetoacetate was observed; conversely, acetoacetate (up to 40 mM) partially or completely abolished the observed stimulating effects of acetate, oleate, and 3-hydroxybutyrate. The results suggest that, in intact liver cells, pyruvate is transported into mitochondria in exchange for acetoacetate and that an interrelationship between gluconeogenesis and ketogenesis at the level of mitochondrial pyruvate carrier may exist in the liver.