Protein-Bound Sterols in Rodent Urine

Abstract
Normal rats excreted an average of about 15 µg of cholesterol in the urine daily plus 2 µg of a fast-acting sterol; mice, 2 µg and 0.2 µg, respectively. Chromogenic, chromatographic and chemical evidence suggested the fast-acting sterol to be Δ7-cholestenol. The sterols of rat urine were bound to both albumin and globulin, cholesterol being more concentrated in the globulin fraction. The excretion of cholesterol varied with age, sex, species, and strain; it could be increased greatly by injecting Δ7-cholestenol, somewhat by injecting cholesterol or by feeding a high fat diet, and very slightly by feeding a high protein diet; it was not altered by high dietary cholesterol, by glomerulonephritis due to N,N'-diacetylbenzidine, nor by the presence of a hepatoma. The urinary cholesterol of the rat was 74% unesterified; the fast-acting sterol, 24%. Six to eleven per cent of the total sterol of rat and mouse bladder was found to be fast-acting, all bladder sterol being unesterified.