Changes of fatty acid composition of phospholipids in liver mitochondria and microsomes of the rat during growth.

The fatty acid patterns of rat liver mitochondrial and microsomal phospholipids were analyzed from term fetuses, 1 and 4 days old, and adult rats. The main fatty acids of phosphatidylethanolamine and -choline were stearic and palmitic acids, although the patterns differed slightly. The fatty acid composition of corresponding phospholipids in mitochondria and microsomes was similar. The fatty acid pattern of cardiolipin was dominated by linoleic acid. The most consistent feature of the developmental changes in the fatty acid patterns of all phospholipids studied was a decrease in the relative amount of monounsaturated fatty acids. The percentages of saturated fatty acids in phosphatidylethanolamine and -choline increased during neonatal development. It is suggested that the high levels of fetal monounsaturated fatty acids were due to low availability of polyunsaturated fatty acids.