Substrate specificity of the di/tripeptide transporter in human intestinal epithelia (Caco-2): identification of substrates that undergo H+-coupled absorption
Article first published online: 19 JUL 2012
1994 British Pharmacological Society
British Journal of Pharmacology
Volume 113, Issue 3, pages 1050–1056, November 1994
How to Cite
Thwaites, D. T., Hirst, B. H. and Simmons, N. L. (1994), Substrate specificity of the di/tripeptide transporter in human intestinal epithelia (Caco-2): identification of substrates that undergo H+-coupled absorption. British Journal of Pharmacology, 113: 1050–1056. doi: 10.1111/j.1476-5381.1994.tb17099.x
- Issue published online: 19 JUL 2012
- Article first published online: 19 JUL 2012
- Received May 24, 1994; Revised July 11, 1994; accepted July 15, 1994
- Proton-coupled transport;
- Caco-2 cells;
- cell culture;
- intracellular pH
- 1pH-dependent transepithelial transport and intracellular accumulation of the hydrolysis-resistant dipeptide glycylsarcosine (Gly-Sar) have been demonstrated in the model human intestinal epithelial cell line, Caco-2.
- 2Experiments with BCECF (2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein)-loaded Caco-2 cells demonstrated that dipeptide (Gly-Sar) transport across the apical membrane is coupled to proton flow into the cell.
- 3A range of postulated substrates for the intestinal di/tripeptide carrier were tested for their abilities to: (a) inhibit pH-dependent [14C]Gly-Sar apical-to-basal transport and intracellular accumulation and (b) stimulate H+ flow across the apical surface of BCECF-loaded Caco-2 cell monolayers.
- 4A range of compounds (including Gly-Gly, Leu-Leu, Gly-Gly-Gly, cefadroxil and cephalexin) caused marked acidification of intracellular pH when perfused at the apical surface of Caco-2 cell monolayers. In contrast leucine and D-Leu-D-Leu failed to induce proton flow. The ability to induce proton-flow across the apical surface by these compounds, in this intestinal epithelium, was directly correlated to the relative inhibitory effects on [14C]-Gly-Sar transport and accumulation.
- 5The determination of substrate-induced intracellular pH change in the Caco-2 cell system may provide a useful rapid screen for candidate substrates for absorption via H+-coupled transport mechanisms such as the intestinal di/tripeptide carrier in an appropriate physiological context.