Effects of Carbohydrate Feeding on Serum Lipids and Lipoproteins in the Rat

¹ From the Section on Metabolism, National Heart Institute, National Institutes of Health, Bethesda, Maryland

Fasting in the rat is accompanied by an increase in serum cholesterol concentration reflecting an increase in high-density lipoproteins. The feeding of carbohydrate results in decreases in both low- and high-density lipoproteins, the former occurring acutely, and the latter occurring more slowly. In the fasting rat the injection of protamine, an antiheparin agent, produces an increase in all serum lipids, but the increase occurs in the low-density lipoproteins. In the rat fed carbohydrate this lipemia-inducing effect of protamine is practically abolished. The feeding of carbohydrate has no effect, however, on the rate of clearance of intravenously administered chylomicrons. These phenomena are discussed in relation to current theories of lipid transport.