In Vitro Absorption of Amino Acids by the Small Intestine of Sheep

Abstract

Duodenal, jejunal and ileal sections from sheep were used to study in vitro absorption of valine, threonine and methionine. Everted sections of intestinal segments were formed into sacs and incubated for 45 min at 39 C under an atmosphere of 95% O₂ and 5% CO₂ in Krebs-Ringer bicarbonate buffer containing 5 µmoles of the test amino acid per milliliter. Hydrolyzed tissue and mucosal and serosal fluids were analyzed for amino acid content. The duodenum removed smaller quantities of amino acids from the mucosal fluid than the jejunum, and less (P<.01) than the ileum. Accumulation of valine and methionine by duodenal tissue was not significantly different from the ileal tissue. Tissue accumulation of amino acids by the jejunum was less (P<.05) than in either the duodenum or ileum. The release of amino acids from duodenal tissue to the serosal fluid was small for threonine and methionine, and negative for valine. The jejunum readily removed valine and methionine, but removed only a small amount of threonine from the mucosal fluid. The release of amino acids into the serosal fluid by the jejunum was very slight as compared to the ileum (P<.01). The ileum removed more (P<.01) amino acids from the mucosal fluid and released more (P<.01) into the serosal fluid. The ileum, therefore, appears to be the most active and efficient site of valine, threonine and methionine absorption in sheep. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.