D-glucose transport and concentration in tumoral insulin-producing cells.
The uptake of D-[U-14C]glucose and D-[5-3H]glucose by tumoral insulin-producing cells of the RINm5F line was measured over 3-30 min of incubation at 7-37 degrees C. The apparent distribution space of the hexose ranged from values as low as the L-[1-14C]glucose space to values 10 times higher than the 3H2O space. Although a major fraction of the radioactivity recovered in the cellular pellet corresponded to the metabolites of D-glucose, the results suggested that the transport of D-glucose into the tumoral cells represents a saturable and temperature-dependent process. When D-glucose was measured by an enzymic procedure in cells incubated for 30 min at 37 degrees C in the presence of 50.0 mM D-glucose, the apparent distribution space of the hexose remained lower than the intracellular water space. These results indicate that the RINm5F cells have lost an essential attribute of the glucose-sensing device in normal insulin-producing cells, namely the ability to ensure the equilibration of D-glucose concentrations across the plasma membrane.
D007516:Adenoma, Islet Cell / Q000378:metabolism*; D000818:Animals; D002250:Carbon Radioisotopes; D002460:Cell Line; D005947:Glucose / Q000378:metabolism*; D007340:Insulinoma / Q000378:metabolism*; D007700:Kinetics; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D051381:Rats; D013237:Stereoisomerism; D013395:Sucrose / Q000378:metabolism
D002250:Carbon Radioisotopes; D009004:Monosaccharide Transport Proteins; D013395:Sucrose; D005947:Glucose