Transepithelial dipeptide (glycylsarcosine) transport across epithelial monolayers of human Caco-2 cells is rheogenic

D T Thwaites, G T McEwan, B H Hirst, N L Simmons

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Abstract

Net transepithelial transport (and cellular accumulation) of the dipeptide glycylsarcosine (Gly-Sar), across the apical membrane of human intestinal Caco-2 epithelia, is driven by a proton gradient (Na(+)-free conditions) and displays saturation kinetics (Km 17.4 +/- 5.1 mM, Vmax of 92.8 +/- 15.6 nmol.cm-2.h-1). Net Gly-Sar transport is associated with the stimulation of an inward short-circuit current (Isc). This dipeptide-stimulated Isc is observed in both Na(+)-containing and Na(+)-free conditions, is stimulated by apical acidity, and displays saturation kinetics (in Na(+)-free media at apical pH 6.0, Km of 13.6 +/- 4.5 mM and a Vmax of 284.1 +/- 39.3 nmol.cm-2.h-1). The maximal capacities of Gly-Sar transport and Isc suggest a dipeptide/proton stoichiometry greater than unity (1:3).
Original languageEnglish
Pages (from-to)178-80
Number of pages3
JournalPflugers Archiv : European Journal of Physiology
Volume425
Issue number1-2
Publication statusPublished - Oct 1993

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Keywords

  • Biological Transport
  • Cell Line
  • Dipeptides
  • Electric Conductivity
  • Epithelium
  • Humans
  • Hydrogen-Ion Concentration
  • Intestines
  • Kinetics
  • Protons

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