Characterization of glucose uptake by cultured rat podocytes.

The nonmetabolizable glucose analogue [3H]-2-deoxy-D-glucose (3H-2DG) was used to study glucose transport in cultured rat podocytes. Intracellular accumulation of 3H-2DG was linear up to 20 min and was inhibited by cytochalasin B (80% inhibition) and by phlorizin (20% inhibition). Pretreatment with insulin stimulated the 3H-2DG uptake 1.5-fold. A Hill analysis of the rate of glucose transport yielded a Vmax value of approximately 10 mM and S0.5 of 7.8 mM. The value h = 1.0 for a Hill coefficient confirmed that glucose uptake exhibited a Michaelis-Menten kinetics. Transporters GLUT2 and GLUT4 were expressed in over 90% podocytes. Of the GLUT2- and GLUT4-expressing cells, approximately one-fourth expressed the membrane-bound fraction. We conclude that cultured rat podocytes possess a differentiated glucose transport system consisting chiefly of facilitative GLUT2 and GLUT4 transporters. It seems likely that a sodium-dependent glucose cotransporter may also be present in these cells.