Insulin Binding and Glucose Uptake Differences in Rodent Skeletal Muscles

Insulin binding and 2-deoxy-d-glucose uptake were compared in the soleus, plantaris, and extensor digitorum longus (EDL) muscles, in vitro, since the known biochemical profile of the soleus differs markedly from the other two. The present study showed that insulin binding increased in all three muscles with increasing concentrations of insulin in the range of 0.2-30 nM. However, the increase in binding of insulin to soleus at each insulin concentration exceeded that observed in the other two muscles (P less than 0.05). Differences between the plantaris and EDL were not significant. The quantity of insulin bound at each concentration also increased more rapidly in the soleus than in either the plantaris (P less than 0.05) or EDL (P less than 0.05). Basal and insulin-stimulated uptake of 2-deoxy-d-glucose was also greater in the soleus than in the other muscles (P less than 0.05). Maximal 2-deoxy-d-glucose uptake occurred at 1 nM insulin in each of the three muscles. These results indicate that in metabolically distinct types of skeletal muscles glucose uptake can differ markedly, and this is related to differences in the insulin binding capacities of these muscles.