Lipoproteins in experimental nephrosis: plasma levels and composition.

Experimental nephrosis was induced in rats by administration of puromycin aminonucleoside and the levels of plasma lipoproteins were examined 7 days later and compared to controls. As determined by density ultracentrifugation, VLDL, IDL, LDL, and HDL protein levels were increased by 8, 4, 5, and 5 times, respectively. These increases were accompanied by changes in lipid and apoprotein composition. The VLDL, IDL, and LDL fractions contained less triglyceride and more phospholipid and cholesterol, while HDL lipid composition was not altered. The apoprotein composition of VLDL and IDL were not measurably altered, but LDL contained less apoE. HDL had a markedly abnormal composition characterized by an almost complete absence of apoA-IV and apoE, increased apoA-1, and decreased apoC. While increased hepatic synthesis can account for much of the observed hyperlipoproteinemia in nephrosis, the changes in lipoprotein composition suggest impaired catabolism as a contributory factor.