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In experimental models of gastroenterological disease, the soluble fiber gum arabic (GA) acts as a proabsorptive adjuvant. This study investigated which specific transport pathway(s) are affected by GA. Rat jejunum was perfused under anesthesia with a standardized oral rehydration solution (ORS) containing D-glucose, with or without GA (2.5 g/liter). In some preparations either phloridizin, a competitive inhibitor of Na+-coupled D-glucose transport, or phloretin, an inhibitor of basolateral glucose transport, were added to the ORS, with or without GA. Diffusion and paracellular transport changes due to GA were evaluated with L-glucose and [14C]polyethlyene glycol 4000 (PEG). GA partially reversed water, Na+, and D-glucose absorption inhibition induced by phloridzin and normalized water and Na+ absorption in the presence of phloretin. GA also increased absorption of water, Na+, and PEG from an L-glucose ORS. The data suggest that GA does not act via Na+ dependent mechanism(s), but stimulates transcellular and/or transjunctional transport pathways; therefore GA may be useful to increase absorption of solutes transported by diffusion. |
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