TRANSLOCATION OF THE BRAIN-TYPE GLUCOSE TRANSPORTER LARGELY ACCOUNTS FOR INSULIN STIMULATION OF GLUCOSE-TRANSPORT IN BC3H-1 MYOCYTES

Insulin-stimulated glucose transport was examined in BC3H-1 myocytes. Insulin treatment lead to a 2.7 ± 0.3-fold increase in the rate of deoxyglucose transport and, under the same conditions, a 2.1 ± 0.1-fold increase in the amount of the brain-type glucose transporter (GLUT 1) at the cell surface. It has been shown that some insulin-responsive tissues express a second, immunologically distinct, transporter, namely GLUT 4. We report here that BC3H-1 myocytes and C2 and G8 myotubes express only GLUT 1; in contrast, rat soleus muscle and heart express 3-4 times higher levels of GLUT 4 than GLUT 1. Thus translocation of GLUT 1 can account for most, if not all, of the insulin stimulation of glucose transport in BC3H-1 myocytes. On the other hand, neither BC3H-1 myocytes nor the other muscle-cell lines are adequate as models for the study of insulin regulation of glucose transport in muscle tissue.