Submitted on March 26, 2007
Revised on May 10, 2007
Accepted on May 11, 2007
Proteinuria increases oxylipid concentrations in VLDL and HDL, but not LDL particles in the rat
John W. Newman, George A. Kaysen, Bruce D. Hammock, and Gregory C. Shearer
Western Human Nutrition Research Center, USDA - Agricultural Research Service, Davis, CA 95616
Corresponding Author: jnewman{at}whnrc.usda.gov
We previously established that proteinuria alters the apolipoprotein content of lipoproteins. This study was conducted to establish whether proteinuria also alters the concentrations of oxidized lipids within lipoprotein density fractions. To this end we induced passive Heymann nephritis in Sprague Dawley rats and measured an array of alkaline-stable oxylipids in VLDL, LDL and HDL particles. Proteinuria increased the total oxylipid amounts in the HDL and VLDL fractions. More importantly these levels were increased when expressed per unit lipoprotein protein, indicating that the oxidized lipid load per particle was increased. Epoxides and diols increased ~2-fold in HDL and ~5-fold in VLDL, while LDL showed ~2-fold decreases. The HETEs and HODEs increased >4-fold in HDL and >20-fold in VLDL, while LDL showed ~2-fold decreases in the HODEs. Therefore, nephrotic syndrome alters the lipoprotein oxylipid composition independently of an increase in total lipoprotein levels. These proteinuria-induced changes may be associated with the cardiovascular risk of lipoprotein oxidation.