The structural requirement for C 1OH for the active transport of d-mannose and 2-deoxy- d-hexoses by renal tubular cells

Abstract

The transport of methyl-α-glycopyranosides of d-mannose, 2-deoxy- d-glucose and 2-deoxy- d-galactose, as well as of 1,5-anhydro-2-deoxy- d-glucitol in slices of rabbit kidney cortex was investigated. 1. 1. In contrast to the respective actively transported hexoses, their methyl-glycopyranosides (0.1–1 mM) were not accumulated in the cells against marked concentration gradients. The entry of the glycosides into the cells was not significantly affected by 0.5 mM ouabain or absence of Na +, and was only slightly inhibited by 0.5 mM phlorizin. 2. 2. The glycopyranosides (5 mM) did not inhibit the active transport of the respective hexoses (1 mM). 3. 3. 1,5-Anhydro-2-deoxy- d-glucitol (0.1–1 mM) was not accumulated in the cells against its concentration gradient, and its entry was not affected by 2-deoxy- d-glucose. Conversely, the active transport of 2-deoxy- d-glucose (1 mM) was not significantly inhibited by a 5-fold molar excess of its 1-deoxy-derivative. 4. 4. It is concluded that, as opposed to the structural requirements for the transport of d-glucose and d-galactose, C 1OH is essential for the interaction with the carrier(s) mediating the active transport of d-mannose, 2-deoxy- d-glucose and 2-deoxy- d-galactose.