Changes In Phospholipid Composition Research Articles

Composition of subcellular constituents of aortic intima plus inner media isolated by differential and density gradient centrifugation

The phospholipid composition of subcellular components of aortic intima plus inner media from rhesus monkeys has been determined in an effort to explain the marked age-related changes in phospholipid composition of this tissue. The sphingomyelin concentration of aortic intima plus inner media from fetuses and young infants of various ages was less than half that of adult animals. Sphingomyelin was present in high concentrations in all fractions of adult aorta separated by differential ultracentrifugation, but comprised a high proportion of total phospholipid in the light microsomal fraction and a relatively low proportion of the cell sap phospholipids. Sphingomyelin levels of different liver subcellular fractions were essentially identical, and the sphingomyelin concentration in all fractions was low. Aortic microsomal subfractions isolated by gradient ultracentrifugation also had variable phospholipid compositions. The subfraction richest in sphingomyelin was shown by electron microscopy to consist of agranular vesicular membranes that were similar to the liver microsomal subfractions of similar density. The possibility that the agranular membranes of aorta were derived in part from plasmalemma was discussed.