Susceptibility of non-HDL fraction to oxidation in experimental nephrotic syndrome

Abstract

Hyperlipidemia is a striking feature of nephrotic syndrome (NS) and the lipid profile seen in NS is accepted as atherogenic. Both low density lipoprotein (LDL) and very low density lipoprotein (VLDL) are apolipoprotein B-containing lipoproteins which are accepted as atherogenic. Oxidized-LDL (ox-LDL) has been suggested to play a fundamental role in atherogenesis. In this study, male Sprague-Dawley rats were made nephrotic by a single intraperitoneal injection of puromycin aminonucleoside (100 mg/kg body weight). We found significant elevation in serum triglycerides, total cholesterol, malondialdehyde, vitamin E levels and total cholesterol/vitamin E ratio and decrease in total protein and albumin levels in the NS group (n:8) compared with the control group (n:9). High density lipoprotein (HDL)-cholesterol and free fatty acid levels were not significantly different between these two groups. Apolipoprotein B-containing lipoproteins (non-HDL fraction) were separated by precipitation and amount of thiobarbituric acid-reactive substances (TBARS) of non-HDL fraction were measured after 60, 90, 120, 180 minutes of incubation with copper sulphate. TBARS levels of non-HDL fraction were significantly higher in the NS group compared with the control group at all of the time periods above. In nephrotic animals, the increased lipid peroxidation was influenced by serum lipids.