Glucose uptake in relation to metabolic state in perfused rat hind limb at rest and during exercise

A modified rat hindlimb perfusion technique, aimed at studying factors of importance for glucose uptake at rest and during exercise, is presented. The modifications involved cannulation of the femoral artery and femoral vein in the groin, instead of the aorta and caval vein. This modification gives a number of advantages, among others the possibility of using the contralateral leg as control, perfused or nonperfused. The muscle tissue was well preserved after 40 min of perfusion, as judged from normal levels of muscle metabolites. The glucose uptake at rest was dependent on glucose delivery (glucose concentration times blood flow) as well as insulin concentration. During exercise, induced by sciatic nerve stimulation, glucose uptake, lactate production and oxygen uptake increased. The glucose uptake during exercise was closely related to the metabolic state of the muscle tissue. Thus, the glucose uptake was negatively correlated with the ATP/ADP ratio and the creatine phosphate level, and positively correlated to the lactate level in both soleus and gastrocnemius muscle. The results suggest that the level of the glucose uptake in exercising muscles is determined by the energy state of the muscle tissue.