Optimal conditions for analyzing HDL2 cholesterol in small amounts of rat plasma have been studied using different concentrations of dextran sulfate and MgCl2 to precipitate lipoproteins containing apolipoprotein B and/or apo E. When the MgCl2 level was 91 mM, the supernate cholesterol was rather constant at a level of about 50-60% of the total plasma cholesterol concentration. Immunochemical determination of the apo A-I content indicated that no major losses of the HDL2 fraction took place under these conditions. The recovery of about 96% of HDL2 lipoproteins after the precipitation of rat plasma and the almost complete absence of lipoproteins belonging to the VLDL, LDL and HDL1 fractions was demonstrated by agarose gel electrophoresis. Thus, the method should be suitable for screening the HDL2 cholesterol content in small volumes of rat plasma.
The effect of dietary protein on lipid levels of serum and liver and mineral contents of bone tissue was studied in female rats by using 13 semi-purified diets differing with respect to protein source. The diets were characterized with regard to contents of protein, amino acids, fat, crude fiber, phytate, zinc, copper, iron, magnesium, calcium, sodium, potassium, tocopherol and metabolizable energy. Six of the proteins tested were of animal origin and six proteins used were plant proteins. Each diet was fed at a 20% protein, 10% fat level. There was a large variation between groups in the serum content of lower density lipoproteins (VLDL + LDL). Rats fed plant protein diets showed values in a lower range than rats consuming animal protein diets. Triglyceride values showed a similar tendency. A comparison of dietary amino acid composition and blood lipid parameters revealed a significant negative correlation between dietary arginine content and serum VLDL + LDL levels (r = 0.863; P < 0.01). Group differences in total serum cholesterol were also observed. However, this variation was within the same range in animal as well as plant protein diets. Serum tocopherol levels were correlated to the total dietary intakes of tocopherol. No significant trend was observed for the mineral content of bone tissue or for the total lipid content of liver with regard to class of dietary protein. However, all rats fed a blood protein diet developed fatty livers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.