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Glutamine reduces phorbol-12,13-dibutyrate-induced macromolecular hyperpermeability in HT-29Cl.19A intestinal cells
L Kouznetsova1, P B Bijlsma, P A van Leeuwen
1Department of Surgery, Free University Hospital, Amsterdam, Institute of Neurobiology, Faculty of Biology, University of Amsterdam, The Netherlands.
Background:
Loss of mucosal integrity is associated with intestinal hyperpermeability, which may be inhibited by glutamine. The nature of this effect is unknown. The effect of glutamine on protein kinase C (PKC)-mediated hyperpermeability in HT-29Cl.19A intestinal cells was studied.
Methods:
Confluent monolayers of HT-29C1.19A cells were cultured on permeable filters and mounted in Ussing chambers for permeability studies. Apical to basolateral transepithelial permeability for intact horseradish peroxidase (HRP) was determined. Phorbol-12,13-dibutyrate (PDB) was used to activate PKC-mediated hyperpermeability, and the effect of glutamine (0.6 mmol/L) was studied.
Results:
Two hours of PDB stimulation increased the HRP flux, reaching five times control values after 4 hours. Bilateral exposure to glutamine for 4 hours reduced PDB-induced hyperpermeability (37%). Preincubation with glutamine 2 hours before PDB stimulation showed an earlier and greater effect (3 hours, 43%; 4 hours, 50%). This bilateral effect of glutamine was mimicked by separate apical exposure. Basolateral exposure alone had no effect.
Conclusions:
Glutamine rapidly reduced the PKC-mediated hyperpermeability for HRP in HT-29Cl.19A intestinal cells. The dependency on apical exposure suggests that glutamine may be more effective when delivered by the enteral route.