ATHEROSCLEROSIS IN CEBUS ALBIFRONS MONKEYS .1. STEROL METABOLISM

Adult and young male and female Cebus albifrons monkeys exhibit differences in levels of serum cholesterol in response to cholesterol-containing diets; adult males had the highest levels, young males the lowest, and females of either age had values that were intermediate between the two groups of males. No differences were detectable among similar age and sex groups maintained on control diets to which no cholesterol was added. The kinetic characteristics of the disappearance of cholesterol-14C-containing lipoprotein were studied treating the system as a two-pool model. These studies indicated that adult males have a larger amount of cholesterol than do the other groups of monkeys in that pool which is represented by plasma plus those tissues that are in ready equilibrium with it. Similarly, adult males clear from their plasma each day a larger absolute amount of cholesterol, up to 200 mg/day, but this amount represents a smaller fraction of the total cholesterol present in this plasma-tissue pool. Using an isotopic method, the excretion of fecal bile acids and neutral sterols was studied. Results suggest that a large percentage of the sterol cleared from the plasma each day is excreted in the feces, and is made up of approximately equal amounts of bile acids and neutral sterols. Analysis of representative tissues of the animals for cholesterol, however, indicate that monkeys which showed the maximum elevation of serum cholesterol also had an expanded whole-body cholesterol pool. The distribution of cholesterol-14C in the tissues of the monkeys was studied after the semilogarithmic plasma die-away curve became linear with time. Results indicated a high degree of individuality among the different monkeys, and among different tissues from the same monkey. © 1968 Academic Press Inc.