Absorption rates of L-tryptophan, L-methionine, and L-methionyl-L-tryptophan by rat intestine in vitro and in vivo.
The absorption rates of L-tryptophan, L-methionine, and L-methionyl-L-tryptophan were determined by both the everted sac and the tied loop method with rat intestines. In the everted sac method, high concentrations of L-tryptophan or L-methionyl-L-tryptophan caused anomalous inhibition of absorption of L-tryptophan and L-methionine. The rates of absorption of both L-tryptophan and L-methionyl-L-tryptophan decreased markedly at concentrations higher than 2-3mM. This inhibition was not observed in the tied loop method. Chromatographic, electrophoretic, and microscopic studies suggested that such decreases in absorption rate were caused mainly by decomposition of L-tryptophan to some basic incubation products containing tryptamine with consequent damage to the mucosal surface of everted sacs during long-term incubation. In the tied loop method, L-methionyl-L-tryptophan was absorbed more rapidly than either of the constituent amino acids in equimolar mixture.
Sakamoto
K
K
Laboratory of Nutrition, Otsuma Women's University, Tokyo, Japan.
Ryu
K
K
Yabe
Y
Y
D000818:Animals; D004151:Dipeptides / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000633:toxicity; D066298:In Vitro Techniques; D007408:Intestinal Absorption; D007421:Intestine, Small / Q000293:injuries / Q000378:metabolism / Q000473:pathology; D007700:Kinetics; D008297:Male; D008715:Methionine / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000633:toxicity; D051381:Rats; D011919:Rats, Inbred Strains; D014364:Tryptophan / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000633:toxicity
D004151:Dipeptides; C075587:methionyltryptophan; D014364:Tryptophan; D008715:Methionine