Increased glucose transport in nonexercising muscle

Changes in blood flow and muscle glycogen in nonexercising muscle during exercise suggest that glucose transport may be increased in nonexercising muscles. Therefore, we compared 3-O-methyl-D-glucose (3-MG) transport in exercised and nonexercised perfused rat hindlimb muscles (soleus, plantaris, and red and white gastrocnemius), in the absence and presence of insulin (30 nM). Specifically, the following four treatments were used: 1) normal rest, 2) normal exercise animals (90 min running 15 m/min, 8% grade), 3) hindlimb-suspended animals at rest (90 min), and 4) hindlimb-suspended animals while exercising on the forelimbs (90 min running 15 m/min, 8% grade). In separate groups of animals, it was shown from the analyses of the electromyographic interference patterns that muscle activity was sharply reduced in hindlimb-suspended muscles both at rest and during exercise (soleus and plantaris). Glycogen decrements were also observed in nonexercising muscles during exercise (soleus, plantaris, and red gastrocnemius; P less than 0.05), although these decrements were less than in the exercised muscles (P less than 0.05). Glucose transport differed among muscles (soleus = plantaris greater than red gastrocnemius greater than white gastrocnemius), and typical increments were observed after exercise (P less than 0.05) and with insulin stimulation (P less than 0.05). An additive effect of insulin and exercise was also observed (P less than 0.05). In nonexercised muscles with no insulin in the perfusate, an increase in 3-MG transport occurred (P less than 0.05). In the presence of insulin, an increase in 3-MG transport was also observed in the nonexercised red and white gastrocnemius muscles (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)