Phospholipid metabolism in endoplasmic reticular membranes in rats fed high-carbohydrate diet

Abstract

1. 1. The composition and metabolism of phosphatidylcholine and phosphatidylethanolamine components of the rough and smooth endoplasmic reticulum fractions in liver have been studied in rats fed chow, fasted 48 h and refed with high-carbohydrate diet after 48 h fasting. 2. 2. High-carbohydrate fed rats showed a large increase in neutral lipid levels in liver and plasma. Labelling of [1- 14C]palmitic acid in liver triglycerides was higher in this group of rats. Compared to the chow-fed rats, there was a reduced incorporation of fatty acid into plasma triglycerides of the high-carbohydrate fed rats. 3. 3. Phosphatidylethanolamine levels showed a marked decrease in both smooth and rough endoplasmic reticulum fractions of high-carbohydrate fed rats. Phosphatidylcholine levels showed a significant decrease only in the rough microsome fraction in these rats. 4. 4. Linoleic and arachidonic acid concentrations of the phospholipids decreased to a low level in the submicrosomal fractions of high-carbohydrate fed rats. These two fatty acids were virtually absent (a decrease of 92–96%) in the phospholipids of rough microsome fraction. Fatty acid incorporation into the phospholipids of the rough microsomes was almost completely inhibited in high-carbohydrate fed rats. 5. 5. Alterations of submicrosomal phospholipid metabolism is probably related to the changes in lipogenesis and in lipid transport observed on refeeding high-carbohydrate diet.