Abstract
The effect of alloxan on cultured rat pancreatic endocrine cells was investigated by following changes in the incorporation of D-[U-14C]glucose into proteins (chloroform/methanol-insoluble fraction) and lipids (chloroform/methanol-soluble fraction). Cultured cells exposed to either alloxan or alloxan plus D-glucose anomers (16.7 mM) at 37°for 5 min were incubated in a medium containing D-[U-14C]glucose at 37°for 60 min. Alloxan at concentrations of 1.25 and 6.25 mM produced inhibitory effects on incorporation into proteins but had no effect on incorporation into lipids. Incorporation into both proteins and lipids was inhibited by 31.2 mM alloxan. The combination of 1.25 mM alloxan plus 16.7 mM D-glucose anomers synergistically reinforced the inhibitory effect of alloxan on the incorporation of labeled glucose into proteins and lipids. In addition, the action of alloxan was more effective in the presence of the β anomer than the α anomer. SDS-polyacrylamide gel electrophoresis of cells labeled with D-[U-14C]glucose indicated the involvement of cell components having molecular weights of more than 200000, 120000, 52000 and 20000. In conclusion, the present data indicate that alloxan inhibits the incorporation of D-[U-14C]glucose into proteins and lipids in cultured pancreatic endocrine cells and that the β anomer of D-glucose reinforces the action of alloxan to a greater extent than the α anomer.
