Turnover of lipid components in liver microsomes, mitochondria and plasma membrane of 6-, 12- and 24-month old rats.

The turnover of lipid was examined in the livers of 6-, 12- and 24-month old rats. Heterogeneity of turnover was noted for each membrane fraction. The lipid turnover rate was highest in 12-month old rats and was the same in 6- and 24-month old rats. The higher rate of lipid turnover at 12 months was observed in both the neutral and polar lipid components of the liver membranes. In the polar lipid fractions isolated from the microsomal and mitochondrial membranes the increase in lipid turnover rate at 12 months was related to increase in the turnover of phosphatidylethanolamine.