Uranyl inhibition of the transport of surgars by the intestinal mucosa

Abstract

Sugar absorption in rats is studied by the Sols and Ponz's method. Four succesives absorption in an intestinal loop invivo are performed in each animal. With hexoses, in the first and third absorptions sugar Solutions had no uranyl and in the second and fourth ones they were with uranyl present. With 1-arabinose, uranyl only was present in the third absorption, because the absorption rate becomes regular from the second one.

D-Glucose and D-galactose absorption is notably inhibited with uranil 5 x lO--* M (Tables I and II). Inhibition of D-fructose absorption requires 10-3 M concentration and is very much lower than upon the other hexoses (Table III). Uranyl has no effect (10-3 M) on the L-arabinose absorption.

Uranyl inhibition seems also related to the active transport mechanism, and it is selective.

Uranyl forms complexes with components of the membrane envolved in the sugar transport. The binding reaction must be not instantaneous. These complexes are stables against physiologic saline Solutions, but are solved by EDTA. Efectively, EDTA treatment complete^ reversibilizes uranyl inhibition, through its quelating action.