Proximo-distal gradient of Na+-dependent D-glucose transport activity in the brush border membrane vesicles from the human fetal small intestine |
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Authors: | C Malo A Berteloot |
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Affiliation: | Membrane Transport Research Group, Department of Physiology, Faculty of Medicine, University of Montreal, CP 6208, succursale ‘A’, Montreal, Quebec H3C 3T8, Canada |
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Abstract: | Brush-border membrane vesicles were isolated from the jejunum and ileum of 17-20-week-old normal human fetuses and found to be highly enriched in sucrase activity with less than 5% contamination by basolateral membranes. Time course studies of D-glucose uptake clearly showed a transient, phlorizin-sensitive, and Na+-dependent accumulation of sugar into these vesicles. Higher maximum overshoot values and initial rates of D-glucose uptake were recorded in jejunal as compared to ileal vesicles while low substrate binding to the membranes, identical intravesicular volumes and equivalent dissipation of the Na+-gradient were found in the two preparations. It was concluded that a fully functional Na+-D-glucose cotransport system is present with a proximo-distal gradient of activity during the early gestation period. |
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