Dietary effects on serum lipoproteins of dyslipoproteinemic baboons with high HDL1.

Some progeny of baboons (Papio sp.) selectively bred for a high response of serum cholesterol to an atherogenic diet have high serum levels of unusual lipoproteins with flotation rates of F degrees 1.20 9-28, intermediate between those of low and high density lipoproteins (HDL). They are similar to the fraction of HDL commonly called HDL1. We conducted a cross-over experiment to determine the roles of dietary cholesterol and saturated fat in eliciting these lipoproteins in the progeny of two affected sires. Half of the progeny of each sire manifested the trait (high HDL1 phenotype) while consuming an atherogenic diet and half did not (low HDL1 phenotype). While consuming a chow diet, high HDL1 progeny had higher total serum cholesterol concentrations than did low HDL1 progeny. This difference was exaggerated when the animals consumed diets enriched in either cholesterol or saturated fat (lard), and was greatest when the diet contained both. High HDL1 animals also had considerably higher serum apo E concentrations, and slightly higher serum apo A-I concentrations. High HDL1 progeny had much higher levels of cholesterol (twofold) and of apo A-I (three- to eightfold) in HDL1 fractions than did low HDL1 progeny. There were significant interactions between HDL1 class and both dietary cholesterol and saturated fat in their effects on other lipoprotein fractions. High HDL1 animals had an exaggerated elevation of cholesterol and apo B in very low, intermediate, and low density lipoproteins in response to dietary cholesterol. They also had an exaggerated elevation of cholesterol in the lighter HDL1 fraction (d = 1.041-1.053), and lesser elevation of cholesterol and apo A-I in HDL2.