Skeletal muscle lipids. 3. Changes in fatty acid composition of individual phosphoglycerides in man from fetal to middle age.

The fatty acids in cardiolipin, choline phosphoglyceride, ethanolamine phosphoglyceride, inositol phosphoglyceride, and serine phosphoglyceride in the human gastrocnemius muscle were studied for changes between early fetal age to middle age. In cardiolipin, choline phosphoglyceride, and ethanolamine phosphoglyceride, the relative total amount of the linoleic acid series increased considerably during the prenatal period and reached maximum values during the first year of life. In inositol phosphoglyceride and serine phosphoglyceride, only slight changes in the sum of fatty acids of the linoleic acid series were found. An increase in the concentration of fatty acids of the linolenic acid series was found in ethanolamine phosphoglyceride and serine phosphoglyceride, while only minor amounts of these fatty acids were present in choline phosphoglyceride and inositol phosphoglyceride and not at all in cardiolipin. During the period studied, the amount of plasmalogen in ethanolamine phosphoglyceride decreased slightly during the first year of life and then remained at 40%. The amount of plasmalogen increased in choline phosphoglyceride from 8% at the middle of the gestational period to 15% 1 yr after birth. The individual phospholipids were found to have characteristic fatty acid patterns.