Fatty Acid Composition of some Cellular Membranes of Fetal Rat Liver

Abstract

The fatty acid composition of lipids of inner mitochondrial membrane, rough and smooth endoplasmic reticulum of adult and fetal rat liver has been determined. Subcellular membranes of fetal liver show a higher content of palmitic acid and oleic acid and a lower content of stearic acid and arachidonic acid as compared to subcellular membranes of the adult liver. The activity of citrate lyase and acetyl-CoA carboxylase of rat liver cytosol has been determined as a function of age. It is concluded that the differences are due to a relativedeficiency of the fatty acid elongation system. The higher degree of saturation of the fatty acids of the phospholipids of the fetal membranes may be the cause of altered permeability properties of these membranes, as illustrated by the slower rate of isoosmotic swelling in the presence of the ammonium salt of some of the Krebs cycle intermediates in fetal rat liver mitochondria.

Particulate and Free Hexokinase in Fetal Rat Liver

“…This binding is therefore not only a property of the hexoki nase isoenzymes (which are present, albeit in different proportions, both in fetal and adult rat liver) but depends also on some specific property of the mitochondrial membranes, which changes during development. Very little is known about membrane-associated changes in mitochondria of rat liver during develop ment, except for the studies of Luit et al (16) and Poliak (17,18). However, these studies predominantly concern the inner mitochondrial membrane and to not as yet permit definite conclusions.…”