Developmental changes in mitochondrial components in liver of newborn rats

Chronological studies on the respiratory function and membrane components of newborn rat liver mitochondria revealed that perinatal mitochondria retained considerably well-coupled oxidative phosphorylation that functioned in sites II and III prior to site I. The ratio of protein to phospholipid contents (mg/mumol) was low in these mitochondria, in which phospholipids were characterized by their high phosphatidylethanolamine contents (43% of the total phospholipids) and low cardiolipin contents (6% of the total), as compared to those of the adult. The fatty acid composition in major phospholipid species was also different from those of the adult. These characteristics altered with development, and the carbamylphosphate synthetase contents markedly increased from 12 to 20% of the total polypeptides in 10 days postnatal time. From these results structural and functional completion of mitochondria accompanying development is discussed from a mitochondrial biogenesis viewpoint.