H(+)-coupled (Na(+)-independent) proline transport in human intestinal (Caco-2) epithelial cell monolayers

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

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

Previously, absorption of L-proline across the apical membrane of the intestinal enterocyte has been attributed to transport via the Na(+)-dependent Imino system. However, net (absorptive) transport of proline across intact Caco-2 cell monolayers was enhanced by acidification of the apical environment, under both Na(+)-containing and Na(+)-free conditions. This Na(+)-independent pH-dependent proline flux was associated with H+ flow across the apical membrane as determined by continuous measurement of intracellular pH. H+/proline symport was associated with an inward Isc in voltage-clamped Caco-2 epithelial layers demonstrating the electrogenic nature of this transport process. In conclusion Caco-2 cells possess an apically-localised, Na(+)-independent, electrogenic H+/imino acid transporter which may play an important role in intestinal proline absorption.
Original languageEnglish
Pages (from-to)78-82
Number of pages5
JournalFEBS Letters
Volume333
Issue number1-2
Publication statusPublished - 25 Oct 1993

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Caco-2 Cells
Proline
Monolayers
Epithelial Cells
Imino Acids
Membranes
Enterocytes
Acidification
Intestinal Absorption
Ion Transport
Fluxes
Electric potential

Keywords

  • Biological Transport
  • Cell Line
  • Epithelial Cells
  • Epithelium
  • Humans
  • Hydrogen-Ion Concentration
  • Intestinal Mucosa
  • Proline
  • Protons
  • Sodium

Cite this

Thwaites, D. T., McEwan, G. T., Cook, M. J., Hirst, B. H., & Simmons, N. L. (1993). H(+)-coupled (Na(+)-independent) proline transport in human intestinal (Caco-2) epithelial cell monolayers. FEBS Letters, 333(1-2), 78-82.

H(+)-coupled (Na(+)-independent) proline transport in human intestinal (Caco-2) epithelial cell monolayers. / Thwaites, D T; McEwan, G T; Cook, M J; Hirst, B H; Simmons, N L.

In: FEBS Letters, Vol. 333, No. 1-2, 25.10.1993, p. 78-82.

Research output: Contribution to journalArticle

Thwaites, DT, McEwan, GT, Cook, MJ, Hirst, BH & Simmons, NL 1993, 'H(+)-coupled (Na(+)-independent) proline transport in human intestinal (Caco-2) epithelial cell monolayers', FEBS Letters, vol. 333, no. 1-2, pp. 78-82.
Thwaites, D T ; McEwan, G T ; Cook, M J ; Hirst, B H ; Simmons, N L. / H(+)-coupled (Na(+)-independent) proline transport in human intestinal (Caco-2) epithelial cell monolayers. In: FEBS Letters. 1993 ; Vol. 333, No. 1-2. pp. 78-82.
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AU - Cook, M J

AU - Hirst, B H

AU - Simmons, N L

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AB - Previously, absorption of L-proline across the apical membrane of the intestinal enterocyte has been attributed to transport via the Na(+)-dependent Imino system. However, net (absorptive) transport of proline across intact Caco-2 cell monolayers was enhanced by acidification of the apical environment, under both Na(+)-containing and Na(+)-free conditions. This Na(+)-independent pH-dependent proline flux was associated with H+ flow across the apical membrane as determined by continuous measurement of intracellular pH. H+/proline symport was associated with an inward Isc in voltage-clamped Caco-2 epithelial layers demonstrating the electrogenic nature of this transport process. In conclusion Caco-2 cells possess an apically-localised, Na(+)-independent, electrogenic H+/imino acid transporter which may play an important role in intestinal proline absorption.

KW - Biological Transport

KW - Cell Line

KW - Epithelial Cells

KW - Epithelium

KW - Humans

KW - Hydrogen-Ion Concentration

KW - Intestinal Mucosa

KW - Proline

KW - Protons

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