ラットのバター, マーガリン飼育によるリポ蛋白, 肝細胞膜, 赤血球膜の脂肪酸組成の変化について

Abstract

It is well recognized that a change of fatty acid composition of plasma lipoproteins and cellular membranes alters membrane fluidity, producing significant influences on the functions of membrane-bound enzymes or lipoprotein receptors. It is important, then, to know whether or to what extent dietary fat manipulation may influence the fatty acid composition of lipoproteins and cellular membranes. We studied fatty acid composition of lipoproteins and membranes of hepatocytes and erythrocytes in rats after feeding of different fats.Wister male rats were divided into two groups which received a diet supplemented with either butter or margarine. After several feeding periods plasma levels of lipids and fatty acid composition of phospholipids in high density lipoprotein (HDL), hepatocyte membranes and erythrocyte membranes were examined. Extraction of total lipids from HDL and hepatocyte membranes was conducted by the method of Folch, and from erythrocytes by the method of Rose. Isolation of total phospholipids was done by thin layer chromatography and fatty acid composition was analyzed by gas liquid chromatography.Plasma levels of triglyceride and phospholipid after two weeks of feeding were significantly higher in the butter-fed rats than in the margarine-fed rats. The difference of cholesterol level did not reach a statistical significance.Fatty acid composition of phospholipids in HDL, hepatocyte and erythrocyte showed a characteristic response for each feeding. The level of linoleic acid in HDL, hepatocyte and erythrocyte was higher in the margarine-fed rats and the level of arachidonic in HDL and hepatocyte was also higher in the margarine-fed rats. The level of oleic acid in HDL and hepatocyte and the level of palmitic acid in hepatocyte were higher in the butter-fed rats. These results show that the fatty acid composition in lipoproteins and cellular membranes responds well to a change of dietary fats.