AJP - Cell Physiology, Vol 251, Issue 6 847-C851, Copyright © 1986 by American Physiological Society
D-glucose transport and concentration in tumoral insulin-producing cells
M. H. Giroix, A. Sener and W. J. Malaisse
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.
