Atherogenic diet-induced modification of the subfraction distribution of high density lipoproteins in monkeys.

High density lipoproteins (HDL) were isolated from the plasma of adult male African green monkeys fed control or atherogenic diets and were then subfractionated in a density gradient by centrifugation at 50,000 rpm, 20 degrees C for 18 hours in the Beckman VTi50 vertical rotor. Material from the gradient was pooled into six subfractions for further analysis. With increasing density across the gradient, the subfractions had progressively decreasing flotation rates, molecular weights, apo A-I/apo A-II mass ratios, lipid percentages of mass, and average sizes. Apoprotein content per particle was reasonably constant compared to lipid content. The physical and chemical properties of the HDL subfractions suggested that the gradient separated three subclasses of HDL equivalent to HDL 2b, HDL 2a, and HDL3 of human beings. When values among animals were compared, the atherogenic diet shifted the relationship between total plasma cholesterol concentration and total HDL concentration from a positive to a negative correlation. The subfractions most affected were those of d less than 1.10 g/ml (HDL2b), while the 1.10 less than d less than 1.13 g/ml (HDL2a) subfractions were affected to a lesser degree; the more responsive the animal to dietary cholesterol, the lower was the mass concentrations of these subfractions. This pattern suggested that diet-induced changes in HDL2 subfraction particle concentrations may be related to the development of atherosclerosis in African green monkeys; parallel changes in particle composition were not identified.