title: Peptide digestion and absorption in humans: portal vein, hepatic vein, and peripheral venous amino acid concentrations.
abstract: An oligopeptide preparation and an amino acid mixture with an identical composition were administered intraduodenally to a patient with a catheter in the portal vein, and blood samples were collected over time from the portal vein, the hepatic vein, and a peripheral vein to investigate amino acid digestion and absorption. When the oligopeptide preparation was administered, amino acids appeared rapidly in the portal blood and monomodal well-balanced absorption curves were obtained. When the amino acid mixture was given, however, amino acid levels in the portal blood indicated a bimodal pattern of absorption. Evaluation of the kinetics of various amino acids after administration of the two preparations showed that they could be classified into the following four groups: 1) amino acids showing hepatic uptake (threonine, methionine, phenylalanine, lysine, histidine, arginine, serine, and proline), 2) amino acids released from peripheral tissues and taken up by the liver (alanine, glutamine, and glycine), 3) amino acids not showing hepatic uptake (leucine, valine, and isoleucine), and one amino acid released from the liver for peripheral uptake (glutamic acid). These findings suggest that the nature of the protein source and the kinetics of individual amino acids should be taken into account in nutritional therapy and nutritional assessment.
authors.affiliation: Third Department of Surgery, Faculty of Medicine, University of Tokyo, Tokyo.
authors.forename: M
authors.initials: M
authors.lastname: Yamakawa
authors.forename: J
authors.initials: J
authors.lastname: Maeda
authors.forename: K
authors.initials: K
authors.lastname: Sugisaki
authors.forename: T
authors.initials: T
authors.lastname: Fujita
authors.forename: T
authors.initials: T
authors.lastname: Oohara
authors.forename: H
authors.initials: H
authors.lastname: Hara
authors.forename: S
authors.initials: S
authors.lastname: Mitani