Comparative study of density distribution of plasma lipoproteins of normo- and hypercholesterolemic rhesus monkeys and humans.

Density gradient centrifugation was used to characterize the lipoprotein distribution of rhesus monkeys and human subjects with normal and elevated cholesterol levels. The lipoprotein profile of control monkeys differed from that of normal humans in that their density distribution as a whole was shifted to lower density. The most striking difference was that both rhesus high density lipoprotein (HDL) subspecies had densities lower than human HDL3, with one component having a lower, and the other a higher, density than human HDL2. Rhesus monkeys fed a diet supplemented with 0.5% cholesterol and 15% lard were divided into two groups. Those animals with cholesterol levels less than 435 mg/dl had a high apo A-I concentration and HDL subspecies similar to human HDL2 and HDL3, whereas those with concentrations greater than 435 mg/dl had a low apo A-I concentration and HDL species with a density either similar to, or exceeding that, of human HDL3. Low density lipoprotein (LDL) density decreased in both groups of hypercholesterolemic monkeys and was particularly pronounced in animals with cholesterol levels above 435 mg/dl. When the lipoprotein profiles of normal humans were compared with those having hypercholesterolemia, increases in the density of both HDL2 and HDL3 in hypercholesterolemic men and to a lesser extent in the density of HDL2 in women were detected. The results indicate that the overall density distribution of plasma lipoprotein is different between rhesus monkeys and humans, and may vary within each species as a function of the nutritional status. It follows that it is difficult to define lipoprotein classes of one species by using density intervals determined for another. Furthermore, these intervals can be inadequate in identifying lipoprotein classes within an individual before and after dietary manipulations.