Portal absorption of fatty acids in lymph- and portal vein-cannulated rats

Abstract

The route and the rate of the intestinal absorption of [1- 14C]oleic, [1- 14C]-caprylic, and 2-[ 14C]ethyl- n-caproic acids have been studied using lymph- and portal vein-cannulated rats. It was found that 85% of absorbed oleic acid was transported via lymphatic system. However, as much as 15% of absorbed oleic acid was transported directly via the portal system. With short-chain fatty acids, between 94–98% of the absorbed acids were transported via the portal system. Studies on the rate of the intestinal absorption of these acids indicated that 2-ethyl- n-caproic acid was absorbed less completely and subsequently metabolized less effectively than the corresponding straight-chain fatty acid, caprylic acid. Studies on the distribution of radioactivity in lymph lipids showed that most of the radioactivity (85%) was present as triglycerides when [ 14C]oleic acid was administered to lymph and portal vein fistula rats. However, when the 14C-labeled short-chain fatty acids were given, 96–102% of the radioactivity was present as free fatty acids. Studies on the distribution of radioactivity in lipid fractions of portal vein blood showed that 50 and 98–100% of the radioactivity present were in the form of free fatty acids when [ 14C]oleic acid and 14C-labeled short-chain fatty acids, respectively, were administered to lymph and portal vein fistula rats.