Quantitative Effects of Bile Salt and Fatty Acid on Cholesterol Absorption in the Rat

Abstract

The influence of various molar proportions of oleic acid and sodium taurocholate on the absorption of cholesterol and upon the lipid partition of thoracic duct lymph has been studied. In bile fistula rats a marked reduction of all lipid fractions of lymph was evident. The administration of oleic acid, taurocholate and cholesterol, singly or in various combinations to these animal preparations failed to elevate the lipid levels to those found in the fasting control animals having a normal bile circulation. The inclusion of up to 430 mg of taurocholate in an intragastric emulsion containing 50 mg of cholesterol and an excess of fatty acid failed to produce significant absorption of cholesterol, emphasizing the importance of the continuous circulation of the bile constituents for the absorption of cholesterol. In lymph fistula animals a molar relationship of oleic acid, taurocholate and cholesterol of 8:4:1 was found to be most effective for lipid and cholesterol absorption from the intestine and phospholipid production by the intestinal mucosa. Several levels of cholesterol greater than 50 mg were administered in emulsions in which the contents of fatty acid and bile salt were optimum for cholesterol absorption at the 50-mg level. No increase in absorption occurred either in absolute amounts or in percentage of the administered sterol. The results of these studies indicate the necessity of fatty acid, bile salt and cholesterol, present at the same time and in the proper molar amounts, for optimal transfer of fatty acid and cholesterol in the rat.