Effects of L-glucose on sodium reabsorption in the isolated perfused rat kidney.

In the isolated perfused rat kidney, sodium reabsorption is enhanced in the presence of 5.5 mM D-glucose. However, it is unclear whether this effect is metabolic or whether it is due to a requirement for sodium transport in the process of glucose reabsorption. A third possibility is solvent drag. In an attempt to differentiate between these possibilities, kidneys were perfused with the D-glucose isomer, L-glucose (L-G), a nonmetabolizable hexose. At a perfusate concentration of 5.5 mM L-G, per cent L-G reabsorption was approximately 30. Inhibition of L-G reabsorption by D-glucose suggests carrier-mediated transport. In the presence of 5.5 mM L-G, sodium reabsorption approximated 92% during the course of perfusion. When L-G was omitted from perfusate, sodium reabsorption ultimately declined to 85%. Since significant metabolism of L-G was not observed, the results are compatible with the hypothesis that enhanced sodium reabsorption may be brought about by some still to be defined aspect of glucose transport.