Gordon T. A. McEwan

Learn More
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.(More)
We determined the extent of Na+-independent, proton-driven amino acid transport in human intestinal epithelia (Caco-2). In Na+-free conditions, acidification of the apical medium (apical pH 6.0, basolateral pH 7.4) is associated with a saturable net absorption of glycine. With Na+-free media and apical pH set at 6.0, (basolateral pH 7.4), competition(More)
The nature of polycation-induced change in transepithelial permeability was investigated in strains I (tight) and II (leaky) MDCK epithelial monolayers. Apical exposure to poly(L-lysine) (PLL, mol. wt. (MW) approximately 20,000) induced a dose-dependent increase in transepithelial conductance (GT) in both strains which correlated with increasing(More)
The polarised nature of the increase in paracellular permeability induced by Ca(2+)-chelation with EGTA was investigated in several cultured epithelial cell lines. In strain I MDCK cells (canine kidney cells), a marked decrease (> 90%) in transepithelial electrical resistance (RT) and increase in mannitol and inulin permeabilities were only observed after(More)
beta-Alanine transport across intact human intestinal epithelial (Caco-2) cell layers has been investigated. In Na(+)-containing solutions, net absorptive flux of beta-alanine from apical-to-basal surfaces is small or absent, despite Na(+)-dependent intracellular beta-alanine accumulation across both apical and basal surfaces. Upon apical acidification(More)
Distinct epithelial MDCK cell strains displaying extremes in transepithelial electrical resistance (paracellular permeability) have been established in co-culture and the subsequent cellular behaviour and formation of junctional complexes investigated. After high-density seeding, MDCK strain I and II cells in co-culture are initially randomly distributed(More)
The mucosal surface pH of rat small intestine was measured in vivo. The surface pH in the normal jejunum was 6.20 +/- 0.02 (67) and 7.00 +/- 0.05 (5) in the ileum. Escherichia coli STa toxin induced a rapid and reversible alkalinization of both jejunal and ileal mucosae to a pH of 6.91 +/- 0.08 (10) and 7.67 +/- 0.06 (5) respectively. The synthetic ST(More)
The effect of age on the secretory response of pig small intestine to in vivo challenge by cholera toxin (CT) was investigated. The small intestine of 14-day-old pigs was more sensitive to CT challenge than that of 14-wk-old animals. In the 14-day jejunum CT-induced fluid secretion was five times that observed in the 14-wk tissue. Similarly, the 14-day(More)
1. Human endometrial epithelial cells cultured on porous tissue culture supports formed tight, polarized epithelial monolayers with features characteristic of tight epithelia. Endometrial epithelial layers generated significant transepithelial electrical resistance (750 Omega cm2) and potential difference (15.3 mV), with an inward short-circuit current(More)
Transepithelial apical-to-basal transport and cellular uptake of the non-metabolisable amino acid alpha-methylaminoisobutyric acid (MeAIB) across confluent monolayers of the human intestinal epithelial cell line Caco-2 are enhanced by a transepithelial pH gradient (apical pH 6.0, basolateral pH 7.4). In Na(+)-free conditions (apical pH 7.4, basolateral pH(More)