Hereditary obesity: relation to serum lipoproteins and protein concentrations in swine.

The importance of heredity in determining the cholesterol, lipoprotein, and plasma protein levels has received insufficient attention. All of these have a greater concentration in the blood of short-fat (mesomorphic), castrate, male, miniature pigs than in long-lean (ectomorphic) animals. These differences seem to persist even when weight changes and growth are rapid. We believe that some of the wide variability of blood lipid levels in human beings is due to genetic factors in the heterogeneous human population on varied diets. IN THE hereditary obese-hyperglycemic syndrome of mice, hypercholesterolemia occurs.1 However, association of hyper-cholesterolemia with hereditary obesity in other species is not well documented. The present studies were made on miniature swine of the long-lean and short-fat strains to determine any association between body build and cholesterol-lipoprotein levels. METHODS AND MATERIAL Six dwarf swine, bred at the University of Minne-sota and classified as long-lean or short-fat strains, were obtained when 12 weeks of age.* They were castrate males and had been immunized against cholera. They were fed a diet of ground oats, corn, and SMA formulat with multivitamins and extra vitamin D. Blood samples were taken every 2 weeks. Serum lipoproteins were determined ultracentrifu-gally at a density of 1.21, with KBr-NaCl as described by Lewis, Green, and Page.2 Serum proteins were determined by the moving-boundary-electro-phoresis method of Tiselius as modified by Longs-worth,3 with phosphate buffer at pH 7.8 and ionic strength of 0.16 g. Cholesterol was measured by the method of Abell and associates,4 free cholesterol by the Sperry and Webb5 method, and phospholipids by the Youngburg and Youngburg technic.6 Total protein was determined by the biuret method as modified by Sols.'