Insulin binding and 2-deoxy-D-glucose uptake in fast- and slow-twitch mouse skeletal muscle at 18 and 37 °C

Insulin binding, insulin degradation, and 2-deoxyglucose uptake were examined at 18 and 37 °C in soleus and extensor digitorum longus muscles of mice. Insulin binding and degradation were greater in the soleus than in the extensor digitorum longus at both temperatures (p < 0.05). At 37 °C, binding was decreased in both muscles while percentage degradation was increased in comparison with 18 °C (p < 0.05). Dose–response curves (percentage of binding at 4 nM of insulin) remained the same for both muscles at the two temperatures. Basal (no insulin) 2-deoxyglucose uptake was increased at 37 °C in the extensor digitorum longus but not the soleus. Insulin responsiveness in terms of the amount of 2-deoxyglucose taken up per femtomole of insulin bound was almost identical for the two muscles at 18 °C, whereas at 37 °C it was increased more in the soleus than in the extensor digitorum longus. The results indicate that in the presence of physiological concentrations of insulin (0.2–4 nM), insulin binding trends are...