TISSUE DISTRIBUTION OF C14 AFTER THE INTRAVENOUS INJECTION OF LABELED FREE FATTY ACIDS AND CHYLOMICRONS IN NEPHROTIC RATS*

Abstract

Normal and nephrotic rats were injected intravenously with palmitate-l-C14 Or C14-chylomicrons. Some rats were fasted and some were fed carbohydrate. They were killed 3 or 10 minutes after the injection. Their blood and tissues were analyzed for C14-lipid-soluble content and for lipid chemical composition. The nephrotic rats differed from normal in the following ways: (1) The liver in nephrosis always contained more total radioactivity than normal. The activity per gram of tissue was not increased, and the difference was due to an increase in the size of the organ. (2) Except in animals sacrificed 3 minutes after administration of Cl4-palmitate, the skeletal muscle in nephrosis was less active than normal. The triglyceride content of muscle was reduced, and after carbohydrate feeding the uptake of labeled triglyceride by muscle was negligible. (3) The adipose tissue of nephrotic animals did not respond in the normal way to changes in the nutritional state. The sparing effect of carbohydrate feeding on fat oxidation was not seen after the administration of C14-chylomicrons to nephrotic rats. (4) The elevated triglyceride fraction in the plasma of nephrotic rats retained more radioactivity than normal 10 minutes after the injection of labeled palmitate or labeled chylomicrons. The relative roles of changes in lipid metabolism in liver and at the periphery as primarily responsible for the etiology of nephrotic hyperlipemia are discussed.