Functional Characterization of Dipeptide Transport System in Human Jejunum

摘要: The present studies were performed to determine whether dipeptide absorption in human jejunum exhibits the characteristics of carrier-mediated transport. 15-cm jejunal segments from volunteers perfused with test solutions containing varying amounts either glycylglycine, glycylleucine, glycine, leucine, glycylglycine leucine or glycylleucine an equimolar mixture free glycine and leucine. Jejunal rates both followed kinetics a saturable process. K(m) value millimoles/liter was significantly greater than (43.3+/-2.6 vs. 26.8+/-5.9, P < 0.05); also (42.7+/-7.5 20.4+/-5.4, 0.05). While overlapping occurred among values amino acids dipeptides, transport dipeptides characterized by higher V(max) (in micromoles per minute 15 centimeters) those acids. For example, for 837+/-62 590+/-56, respectively (P 0.02). not affected they competitively inhibited glycylleucine. rate altered selective investigated infusing three mixtures, each two different dipeptides. Among examined, least absorbed. There no significant difference between leucylglycine. above suggest that is mediated carrier which shared neutral acids; COOH- NH(2)-terminal appear be influential imposing affinity sites.