EFFECTS OF ACUTE AND CHRONIC HINDLIMB SUSPENSION ON SENSITIVITY AND RESPONSIVENESS TO INSULIN IN THE RAT SOLEUS MUSCLE

The effects of acute (24 h) and chronic (5 weeks) hindlimb suspension on insulin-stimulated glucose utilization by the rat soleus muscle wer e studied in vitro. Hindlimb suspension resulted in an enhancement of basal glucose transport, lactate production, and glycogen synthesis. A n increase in the sensitivity of these processes to insulin occurred a s early as 24 h and persisted for 5 weeks of the muscle unloading. An increased responsiveness to insulin was found only for glucose transpo rt after 24 h. The present data do not support the concept that the en hanced glucose utilization and improved muscle insulin sensitivity dur ing hindlimb suspension are related to muscle atrophy, which is not ob served in the early stage of muscle unweighting.