The Effects of Insulin and Metformin on Glucose Uptake in L8 Myotubes

The establishment of in vitro cell culture systems is a useful approach in biomedical research studies to assist understanding of in vivo events. In this study, we have explored the effects of insulin and the hypoglycemic drug metformin on glucose uptake activity, and the possibility of using L8 cells for the studies of glucose transport was investigated. Serum deprivation caused a 35% reduction in basal glucose uptake by L8 myotubes. In the absence of serum, insulin showed a dose-related increase glucose stimulation. Insulin (100 nM) stimulated glucose uptake approximately 2.27±0.40-fold by increasing membrane translocation of GLUT4 from the intracellular compartment. Metformin (1-2 mM) also mediated a 2-fold increase in glucose uptake in the absence of insulin. Exposure of L8 myotubes pretreated with metformin to 100 nM insulin caused further activation of glucose uptake. Our study demonstrated that L8 myotubes exhibit basal glucose transport activity and respond to glucose uptake stimuli of both insulin and metformin. The results suggest that L8 cells could be used as an alternative cell line for glucose transport studies.