Inhibition of absorption of d-xylose by phlorizin in the anesthetized rat

¹ Department of Medicine, The Johns Hopkins University School of Medicine and Hospital, Baltimore, Maryland

The effect of phlorizin on d-xylose absorption was studied in jejunal and ileal segments of anesthetized rats at different concentrations of the sugar. There was an inhibition of d-xylose absorption (79–92%) at sugar concentrations of 2.5 and 5.0 g/liter. A significant but less striking inhibition was demonstrated at a sugar concentration of 10 g/liter, but no significant inhibition could be demonstrated at a concentration of 50 g/liter. It is postulated that a specific "phlorizin-sensitive" transport mechanism is involved in d-xylose absorption and is the major pathway for absorption at low sugar concentrations. As the sugar concentration increases this mechanism becomes saturated and the amount of sugar transported through it becomes constant, while the fraction transported through a "phlorizin-insensitive" mechanism becomes greater. This would explain why at a relatively high concentration of 50 g/liter no significant inhibition could be demonstrated.

Key Words: d-xylose absorption in vivo • phlorizin • transport mechanisms of sugars

Submitted on July 28, 1964