Mechanism of stimulation of cholesterol absorption by 2-ethyl- n-caproic acid in vivo

Abstract

Studies on the mechanism of stimulation of [7α- 3H]cholesterol absorption by 2-ethyl- n-caproic acid have been carried out in lymph- and portal-vein cannulated rats. About 15% of administered cholesterol was absorbed in 8 h when the sterol was given with oleic acid alone. The administration of 2-ethyl- n-caproic acid together with oleic acid and cholesterol significantly increased the absorption of cholesterol to 23%. Simultaneous determination of fatty acid absorption and esterification showed that 44% of the fed [1- 14C]oleic acid was recovered in thoracic duct lymph in 8 h, and about 15% of the long-chain acid was transported directly via portal blood. However, in the presence of 2-ethyl- n-caproic acid, only 22% of the administered [1- 14C]Oleic acid was recovered in lymph, while 40% was transported directly into portal system. This effect of the branched-chain fatty acid was most pronounced 4–8 h after feeding. In this group there was a reduction in total lymph triglycerides and a slight increase in lymph free fatty acids. These data support the earlier suggestion that the primary effect of 2-ethyl- n-caproic acid is inhibition of triglyceride synthesis in intestinal mucosa, resulting in increased transport of free fatty acids via portal blood and increased availability of fatty acids for cholesterol esterification and absorption.