Sugar transport in isolated rat kidney papillary collecting duct cells.
D-Glucose is an important substrate of energy metabolism and osmolyte synthesis in the renal papillary collecting duct. In order to characterize the cellular entry of D-glucose in this tubular segment, collecting duct cells were isolated from rat kidney papilla and the rate of D-glucose uptake was measured indirectly by monitoring the D-glucose-dependent O2 uptake in the presence of the uncoupler CCCP. D-Glucose uptake was found to be sodium-independent and not sensitive to phlorizin even at a concentration of 10(-3) M. Uptake was, however, completely inhibited by 10(-5) M cytochalasin B and 10(-4) M phloretin. The apparent Ki for cytochalasin B was 1.5 x 10(-6) M and for phloretin 2.0 x 10(-5) M. Studies on the substrate specificity revealed that at 1 mM D-mannose is taken up and metabolized to the same extent as D-glucose. A 50-fold higher concentration of 2-deoxy-D-glucose and 2-amino-2-deoxy-D-glucose inhibited D-glucose uptake completely whereas alpha-methyl-D-glucoside, D-allose, and D-galactose were without effect. Under conditions where D-glucose utilization was maximally stimulated an apparent Km of 1.2 mM and a Vmax of 1 mmol D-glucose/g protein.hour was found for D-glucose uptake. These results indicate that the D-glucose uptake into papillary collecting duct cells is probably mediated by a transport system similar to the one found in basal-lateral membranes of polarized renal, intestinal, and liver cells as well as in nonpolarized fat cells and erythrocytes.
Grunewald
R W
RW
Max-Planck-Institut für Systemphysiologie, Dortmund, Federal Republic of Germany.
Kinne
R K
RK
D000818:Animals; D003571:Cytochalasin B / Q000494:pharmacology; D005260:Female; D005947:Glucose / Q000493:pharmacokinetics*; D066298:In Vitro Techniques; D007679:Kidney Medulla / Q000166:cytology* / Q000187:drug effects; D007684:Kidney Tubules / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D010693:Phloretin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014475:Uncoupling Agents / Q000494:pharmacology
D014475:Uncoupling Agents; D003571:Cytochalasin B; D005947:Glucose; D010693:Phloretin