Effects of the degree of saturation of dietary fat on the hepatic production of lipoproteins in the African green monkey.

F L Johnson,R W St Clair,L L Rudel

doi:10.1016/s0022-2275(20)34354-6

Abstract

The cholesteryl ester content of plasma low density lipoproteins (LDL) in monkeys has previously been shown to be related to the rate of hepatic cholesterol secretion and cholesteryl ester content of newly secreted lipoproteins in the isolated perfused liver. In the present studies, African green monkeys were fed diets containing cholesterol and 40% of calories as either butter or safflower oil in order to determine the effects of saturated versus polyunsaturated dietary fat on hepatic lipoprotein secretion. The rate of cholesterol accumulation in liver perfusates was correlated with the size of the donor's plasma LDL, but for any rate, a smaller plasma LDL was found in donor animals of the safflower oil group than in those of the butter group. Hepatic very low density lipoproteins (VLDL) were smaller in the safflower oil group but contained more cholesteryl ester and fewer triglyceride molecules per particle than those from the butter group. Livers from the safflower oil group contained more cholesteryl ester and less triglyceride than those from the butter group. The cholesteryl ester percentage composition of hepatic VLDL resembled that of the liver in each group. The data show that dietary polyunsaturated fat decreased plasma LDL size even though it increased the cholesteryl ester content of lipoproteins secreted by the liver. Therefore, intravascular formation of plasma LDL from hepatic precursor lipoproteins appears to include the removal of relatively greater amounts of cholesteryl esters from the precursor lipoproteins in polyunsaturated fat-fed animals.

Highlights

The cholesteryl ester content of plasma low density lipoproteins (LDL) in monkeys has previously been shown to be related to the rate of hepatic cholesterol secretion and cholesteryl ester content of newly secreted lipoproteins in the isolated perfused liver
Using the isolated perfused liver of African green monkeys, we have demonstrated that dietary cholesterol causes increased hepatic secretion of cholesteryl esters among a large spectrum of lipoprotein types [6]
I n related studies in African green monkeys we found that, relative to polyunsaturated fat, dietary saturated fat increases plasma LDL size and cholesteryl ester content as well as the degree of saturation of plasma LDL cholesteryl esters [7]

Summary

Introduction

The cholesteryl ester content of plasma low density lipoproteins (LDL) in monkeys has previously been shown to be related to the rate of hepatic cholesterol secretion and cholesteryl ester content of newly secreted lipoproteins in the isolated perfused liver. African green monkeys were fed diets containing cholesterol and 40% of calories as either butter or safflower oil in order to determine the effects of saturated versus polyunsaturated dietary fat on hepatic lipoprotein secretion. Hepatic very low density lipoproteins (VLDL) were smaller in the safflower oil group but contained more cholesteryl ester and fewer triglyceride molecules per particle than those from the butter group. Using the isolated perfused liver of African green monkeys, we have demonstrated that dietary cholesterol causes increased hepatic secretion of cholesteryl esters among a large spectrum of lipoprotein types [6]. I n related studies in African green monkeys we found that, relative to polyunsaturated fat, dietary saturated fat increases plasma LDL size and cholesteryl ester content as well as the degree of saturation of plasma LDL cholesteryl esters [7]. T h e isolated livers from these animals were perfused by recirculation with a lipoprotein-free medium in order to study the effects of these dietary fats on hepatic lipoprotein production

Methods

Results

Conclusion