Fatty acid content and composition of phospholipids from the endoplasmic reticulum in developing rat liver.

: The development of enzyme functions of the endoplasmic reticulum in the neonatal rat liver is associated with the formation of membrane-bound phospholipids. This study examined the distribution of fatty acid moieties in isolated endoplasmic reticulum membranes of liver after birth and postnatal development. The content of microsomal phosphatidylcholine, phosphatidylethanolamine, sphingomyelin and lysophosphatidylcholine was raised throughout the postnatal to the adult animal. Acyl components were also increased, especially unsaturated fatty acids such as arachidonic, docosapentaenoic and docosahexaenoic acids. Conversely, saturated components were reduced during maturation, such as palmitic and stearic acids. This work demonstrated that the ontogenesis of the hepatic endoplasmic reticulum correlated with the selectively increased production of discrete phospholipid moieties containing greater amounts of unsaturated fatty acids. Thus, during development, phospholipids are not only required for structural membrane assembly but also display a determining role in the organization of enzyme activity for xenobiotic biotransformation.