Separation and characterization of plasma lipoproteins of rhesus monkeys (Macaca mulatta)

Abstract

A group of 14 adult male rhesus monkeys was maintained on a low cholesterol–high fat diet. Periodically, animals were fasted and blood samples were taken for characterization of the plasma lipoproteins. Complete separation of individual plasma lipoprotein classes was not achieved by traditional sequential ultracentrifugation techniques. Rather, initial separation of lipoprotein classes according to size was effected and density centrifugation was used subsequently for further separation. At least six lipoprotein fractions were identified, each of which was unique as defined by the properties of size, density (d), and electrophoretic mobility. These lipoprotein fractions were characterized by determination of chemical compositions and apoprotein patterns. The lipoproteins present in highest concentration in these monkeys were designated as region IV lipoproteins. This fraction had α-migration on agarose electrophoresis, 1.063 1.050, had pre-β mobility and a size and composition similar to the Lp(a) lipoprotein in plasma of human beings. At least two VLDL subfractions, identified as region I and IIA lipoproteins, were found although both were present in very low concentrations. Region I lipoproteins were larger and contained relatively more cholesteryl ester and more of the apoproteins that migrated with the mobility of apo-B and arg-rich apoprotein in SDS–polyacrylamide gel electrophoresis. Some of the region I lipoproteins were β-migrating by agarose electrophoresis. These results suggested the possibility that a β-migrating VLDL was present in these normal animals.

Keywords

• agarose gel chromatography
• agarose electrophoresis
• apoproteins
• cholesterol
• cholesteryl esters
• high density lipoproteins