Epidermal growth factor up-regulates sodium-glucose cotransport in enterocyte models in the presence of cholera toxin

Devendra I. Mehta, Karoly Horváth, Somchoke Chanasongcram, Ivor D. Hill, Pinaki Panigrahi

Research output: Contribution to journalArticle

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Abstract

Background: Sodium-glucose cotransport by enterocytes is key to the successful implementation of oral rehydration in diarrhea. Confluent, differentiated Caco-2 cells have enterocyte-like characteristics. We have previously shown that short-term incubation of isolated rat jejunal enterocytes with epidermal growth factor (EGF) results in the up-regulation of sodium-glucose cotransport. The aim of this study was to examine the effect of EGF on Caco-2 cells in the presence of cholera toxin. Methods: Caco-2 cells grown on tissue culture dishes were used for glucose and sodium uptake studies and cells were grown on polycarbonate membranes for transport examinations. Effects of EGF on the kinetic parameters of sodium-glucose cotransporter, thymidine transport, and on the activity of Na+/K+-ATPase were examined. The efficacy of basolateral vs apical EGF on sodium and glucose transport was compared after incubation of the monolayers with 10 nmol/L of cholera toxin. Results: EGF increased both glucose and sodium uptake and transport, and we observed a simultaneous increase in the activity of Na+/K+-adenosine Triphosphatase (ATPase). Kinetic studies performed on brush-border membrane vesicles prepared from EGF-incubated confluent monolayers and on intact cells showed an increase in the maximum velocity but not the Michaelis constant, suggesting increased availability of transporters rather than conformational change. This effect was seen within minutes in both of the two putative transporters, high-affinity, low-capacity and low- affinity, high-capacity. There was no acute effect on thymidine uptake. Studies in the presence of cholera toxin demonstrated a significant up- regulation in sodium-glucose cotransport when EGF was applied from the basolateral side; the increase was smaller but significant with apical application. Conclusions: Differentiated Caco-2 cells have two kinetically distinct sodium-glucose cotransporters. Short-term incubation of Caco-2 cells with EGF resulted in an up-regulation of sodium-glucose cotransport and subsequent increase in Na+/K+-ATPase activity. The effect of basolaterally applied EGF was more significant with or without incubation with cholera toxin. The early effect of EGF on glucose and sodium cotransport may have important therapeutic implications in diarrhea and dehydration states. The in vitro model described here uses a homogeneous cell population and provides a versatile system for uptake and transport studies.

Original languageEnglish (US)
Pages (from-to)185-191
Number of pages7
JournalJournal of Parenteral and Enteral Nutrition
Volume21
Issue number4
DOIs
StatePublished - Jan 1 1997

Fingerprint

cholera toxin
Enterocytes
Cholera Toxin
epidermal growth factor
enterocytes
Epidermal Growth Factor
Up-Regulation
Sodium
sodium
Glucose
glucose
Caco-2 Cells
Sodium-Glucose Transport Proteins
cells
adenosinetriphosphatase
uptake mechanisms
Adenosine Triphosphatases
polycarbonate
thymidine
Thymidine

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Cite this

Epidermal growth factor up-regulates sodium-glucose cotransport in enterocyte models in the presence of cholera toxin. / Mehta, Devendra I.; Horváth, Karoly; Chanasongcram, Somchoke; Hill, Ivor D.; Panigrahi, Pinaki.

In: Journal of Parenteral and Enteral Nutrition, Vol. 21, No. 4, 01.01.1997, p. 185-191.

Research output: Contribution to journalArticle

Mehta, Devendra I. ; Horváth, Karoly ; Chanasongcram, Somchoke ; Hill, Ivor D. ; Panigrahi, Pinaki. / Epidermal growth factor up-regulates sodium-glucose cotransport in enterocyte models in the presence of cholera toxin. In: Journal of Parenteral and Enteral Nutrition. 1997 ; Vol. 21, No. 4. pp. 185-191.
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T1 - Epidermal growth factor up-regulates sodium-glucose cotransport in enterocyte models in the presence of cholera toxin

AU - Mehta, Devendra I.

AU - Horváth, Karoly

AU - Chanasongcram, Somchoke

AU - Hill, Ivor D.

AU - Panigrahi, Pinaki

PY - 1997/1/1

Y1 - 1997/1/1

N2 - Background: Sodium-glucose cotransport by enterocytes is key to the successful implementation of oral rehydration in diarrhea. Confluent, differentiated Caco-2 cells have enterocyte-like characteristics. We have previously shown that short-term incubation of isolated rat jejunal enterocytes with epidermal growth factor (EGF) results in the up-regulation of sodium-glucose cotransport. The aim of this study was to examine the effect of EGF on Caco-2 cells in the presence of cholera toxin. Methods: Caco-2 cells grown on tissue culture dishes were used for glucose and sodium uptake studies and cells were grown on polycarbonate membranes for transport examinations. Effects of EGF on the kinetic parameters of sodium-glucose cotransporter, thymidine transport, and on the activity of Na+/K+-ATPase were examined. The efficacy of basolateral vs apical EGF on sodium and glucose transport was compared after incubation of the monolayers with 10 nmol/L of cholera toxin. Results: EGF increased both glucose and sodium uptake and transport, and we observed a simultaneous increase in the activity of Na+/K+-adenosine Triphosphatase (ATPase). Kinetic studies performed on brush-border membrane vesicles prepared from EGF-incubated confluent monolayers and on intact cells showed an increase in the maximum velocity but not the Michaelis constant, suggesting increased availability of transporters rather than conformational change. This effect was seen within minutes in both of the two putative transporters, high-affinity, low-capacity and low- affinity, high-capacity. There was no acute effect on thymidine uptake. Studies in the presence of cholera toxin demonstrated a significant up- regulation in sodium-glucose cotransport when EGF was applied from the basolateral side; the increase was smaller but significant with apical application. Conclusions: Differentiated Caco-2 cells have two kinetically distinct sodium-glucose cotransporters. Short-term incubation of Caco-2 cells with EGF resulted in an up-regulation of sodium-glucose cotransport and subsequent increase in Na+/K+-ATPase activity. The effect of basolaterally applied EGF was more significant with or without incubation with cholera toxin. The early effect of EGF on glucose and sodium cotransport may have important therapeutic implications in diarrhea and dehydration states. The in vitro model described here uses a homogeneous cell population and provides a versatile system for uptake and transport studies.

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