Glucose transport carrier in dog kidney: its concentration and turnover number

Abstract

Varying doses of phlorizin-C14 were infused into dogs and the effects on the maximal capacity of the renal tubules to reabsorb glucose (TmG) were observed. At the time of maximal TmG depression, the kidneys were removed and assayed for phlorizin. The renal concentration of phlorizin which would cause 50% inhibition of glucose transport was determined. From these data, an estimate of the glucose carrier concentration was made and the minimum rate of glucose transport across the brush border membrane per carrier molecule was calculated. These findings are discussed with a view of setting maximum and minimum limits to the transit time of glucose across the plasma membrane, the diffusion coefficient of the glucose-carrier complex through the lipid membrane barrier, the number of carrier molecules per proximal tubule cell, and the molecular size of the glucose-carrier complex.