Inhibitory effect of glucose on the maturation of rat liver mitochondria at birth. Phospholipid and oxidative metabolism

Abstract

(1) The rate of ATP synthesis coupled with succinate oxidation in rat liver mitochondria is low at birth and increases rapidly during the first postnatal hours (Nakazawa, T., Asami, K., Suzuki, H. and Yakawa, O. (1973) J. Biochem. 73, 397–406). A glucose injection given to newborn rats immediately after birth seemed to delay this maturation process. (2) Glucose administration specifically diminished the rate of 32P i incorporation into phosphatidylcholine both in microsomes and in mitochondria while other phospholipids remained unaffected. (3) In newborn rat liver, 32P i incorporation into phospholipids can be explained by de novo synthesis of phospholipids in microsomes followed by transfer to mitochondria with two exceptions: phosphatidylserine and sphingomyelin. Indeed, after a 20-min incorporation of 32P i into phospholipids, the specific radioactivity of phosphatidylserine and sphingomyelin was higher in mitochondria than in microsomes. (4) As far as phospholipid synthesis is concerned, no precursor-product relationship could be observed between light and heavy mitochondria.