Dissociation Between Dietary Effects on Plasma Lipid Concentration and on Plasma Lipoprotein Distribution in Selected Rats

Abstract

The influence of two types of diet on plasma total choles terol and triglycA©ride concentration, and on the lipoprotein distribution was studied in rats with genetically different levels of spontaneous running activity. Genetically active and passive rats of both sexes were fed an open formula cereal based stock diet or a purified diet containing sucrose (47% of calories), coconut fat (35% of calories), and casein (18% of calories) from the age of 3 to 8 months, during which time blood samples were taken three times. In genetically active female rats fed the purified diet the plasma total cholesterol and triglycA©rideconcentrations were higher than in the corresponding groups of rats fed stock diet. In genetically passive rats, on the other hand, no difference in plasma total cholesterol and triglycA©ride concentration between rats fed stock diet and those fed purified diet was observed. The plasma lipid concentration was not related to the level of spontaneous physical activity or to the body weight. The pattern of lipoprotein distribution was very similar in all groups fed the same diet (i.e., actives and passives of each sex). In groups fed the puri fied diet a slight decrease in percentage of the pre-beta and beta fractions, a pronounced increase in a diffuse pre-alpha fraction and a decrease in the alpha fraction was observed as compared with groups fed stock diet. The data for passive rats suggest that a given diet may have an appreciable influence on the lipoprotein distribution without affecting the concentra tion of total cholesterol and triglycA©rides in plasma. J. Nutr. 108: 1823- 1829, 1978.