Uptake of Amino Acids by Mucosa of Rat Colon in vitro

1 Rings of mucosa from rat colon accumulated l-[14C5]valine against a concentration gradient. The accumulation of l-valine was inhibited to some extent by dinitrophenol and cyanide, and more markedly by glycine and l-methionine. l-Lysine was ineffective as an inhibitor. 2 Using everted sacs of colonic mucosa, l-valine, l-citrulline and l-histidine permeated the mucosa from the mucosal fluid to the serosal fluid down a concentration gradient. In experiments with a single amino acid in both the serosal and the mucosal fluids there was always a net loss of amino acid from the serosal fluid. 3 These results are discussed in relation to both tissue accumulation and intestinal absorption of amino acids.