Dextran sulfate precipitable (light) plasma lipoproteins in genetically active and passive rats fed two types of diet

Genetically active and passive female rats were fed a purified sucrose/fat diet or a stock diet from the age of 11 to 27 weeks. The age-related increase in plasma total cholesterol concentration was much more pronounced in active rats fed the purified diet than in active rats fed the stock diet. No significant alteration with age took place in the plasma cholesterol level of passive rats fed the stock or the purified diet. The increase in body weight was somewhat greater in active and passive rats fed the purified diet than in those fed stock diet. The lipoprotein distribution at the age of 27 weeks was estimated using both polyacrylamide gel electrophoresis and dextran sulfate/Ca++ precipitation. As compared with the stock diet, the purified diet effected a decrease in the relative amount of prebeta and beta lipoproteins in both active and passive rats. The major effect was, however, a pronounced increase in the relative amount of dextran sulfate precipitable "light prealpha" lipoproteins with no effect on "heavy prealpha" or alpha lipoprotein percentages. Alpha lipoprotein percentages were slightly higher in active than in passive rats. The results confirm our earlier observation that there might be a dissociation between the dietary effect on the plasma total cholesterol level and on the lipoprotein distribution. The data also suggest that the hyperlipemic sucrose/fat diet causes a shift from the prebeta and beta lipoproteins to the "light prealpha" fractions.