REACTIVE OXYGEN SPECIES ACTIVATE GLUCOSE-TRANSPORT IN L6 MYOTUBES

Under oxidative stress, increased energy requirements are needed To in duce repair mechanisms. As glucose is a major energy source in L6 myot ubes, we evaluated glucose metabolism and transport, following exposur e to glucose oxidase (H2O2 generating system), or xanthine oxidase (O- 2 . and H2O2 generating system), added to the medium. Exposure for 24 h to 5 mM glucose and 50 mU/ml glucose oxidase, or to 50 mu M xanthine and 20 mU/ml xanthine oxidase resulted in significant oxidant stress indicated by increased DNA binding activity of NF-kappa B. Under these conditions, approximately 2-fold increase in glucose consumption, lac tate production and CO2 release were observed. 2-deoxyglucose uptake i nto myotubes increased time and dose dependently, reaching a 2.6 +/- 0 .4-fold and 2.2 +/- 0.7-fold after 24 h exposure to glucose oxidase an d xanthine oxidase, respectively. Peroxidase prevented this effect, in dicating the role of H2O2 in mediating glucose uptake activation. The elevation in glucose uptake under oxidative stress was associated with increased expression of GLUT1 mRNA and protein. The observed 2-deoxyg lucose uptake activation by oxidants was not Limited to the L6 cell li ne and was observed in 3T3-L1 adipocytes as well. (C) 1997 Elsevier Sc ience Inc.