Plasma lipoproteins in rats with experimental biliary obstruction, I. A chemical study

Abstract

Acute biliary obstruction in the rat is associated with striking alterations of the plasma level and the physico-chemical properties of plasma lipoproteins. 1. 1. The level of very low density lipoproteins (VLDL) in plasma increases from 2 to 3 fold. The chemical composition of VLDL is characterized by a high content of phospholipids and cholesterol and by a diminution of the relative content of triacylglycerols and protein. On cellulose acetate electrophoresis, VLDL show a β-mobility. 2. 2. The plasma concentration of low density lipoproteins (1.019–1.063 g/ml, LDL 2) increases several fold above the control level. Phospholipids and unesterified cholesterol are the major components of this fraction which contains only a minute amount of cholesteryl ester (4%) and triacylglycerols (10%). LDL 2 contain a component which migrates to the cathode in 1% agar gel electrophoresis. Separation of LDL 2 by gel filtration on 2% agarose column results in the identification of three subfractions. Subfraction I contains a large proportion of cholesterol and triacylglycerols, subfraction II is rich in unesterified cholesterol and phospholipids whereas subfraction III has a chemical composition fairly similar to that of the control LDL 2. 3. 3. The level of high density lipoproteins (HDL) also increases after bile duct ligation. The chemical composition of HDL 2 (1.063–1.125 g/ml) is characterized by a high content of unesterified cholesterol and phospholipids and by a remarkable reduction in the content of cholesteryl esters and protein.