Na +-independent sugar uptake by rat intestinal and renal brush border and basolateral membrane vesicles

Abstract

1. 1. Uptake of [ 14C]-labelled d-glucose, l-arabinose and d-fructose by intestinal and renal brush border and basolateral membrane vesicles was studied in the absence of Na + . 2. 2. The Na +-independent d-glucose transport system in these membrane vesicles was saturable, sensitive to phloretin, stereospecific and accessible only to d-glucose and d-galactose. 3. 3. Na +-independent l-arabinose transport was not saturable even when its concentration was raised to 300 mM and it was insensitive to phloretin. 4. 4. Na +-independent d-fructose transport demonstrated saturation kinetics with only renal brush border membrane vesicles, but it was not inhibited by either phloretin or phlorizin. 5. 5. These studies indicated that the Na +-independent carrier-mediated d-glucose/ d-galactose transport system of intestinal and renal brush border and basolateral membranes is clearly not shared by other monosaccharides.