Intestinal absorption of methionine and histidine by the chicken

Intestinal absorption of methionine and histidine was studied in adult chickens having permanent Thiry-Vella fistulas. The l isomers of both amino acids were absorbed from the fistulas more rapidly than were the d isomers. At a concentration of 10–3 m, 2,4-dinitrophenol retarded absorption of l-methionine but not of the d form. The absorption of l-histidine was impaired in the presence of equimolar concentrations of either l- or d-methionine. Racemization of d-methionine during absorption could not be demonstrated. The l isomers of both methionine and histidine appear to be absorbed from the chicken intestine by a common specific transport mechanism, with d-methionine being able to participate in at least one stage of this mechanism.