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The Protective Effect of Heating on Skeletal Muscle Atrophy is not Conveyed Through Native Antioxidant Enzymes.  J.T. Selsby and S.L. Dodd, Dept. of Applied Physiology and Kinesiology, University of Florida. Gainesville, FL

   The purpose of this investigation was to determine the effects of whole-body heating on changes in heat shock proteins (HSPs) and antioxidant enzymes in immobilized skeletal muscle.  Twenty-seven, male Sprague Dawley rats were randomly divided into three groups: control (C), immobilized (Im), and immobilized heated (ImH).  Immobilized groups were casted bilaterally so that the feet remained in a plantarflexed position.  The core temperature of animals receiving a heat treatment was elevated to 41-41.5°C for 30 min on alternating days for 10 days.  Animals were then sacrificed, soleus muscles removed, weighed, and frozen in liquid nitrogen.  Soleus muscle mass was significantly reduced by immobilization (30%; p<0.05) and ImH was larger than Im (10%; p<0.05).  HSP 27 and 72 remained unchanged in IM, but were elevated nearly two fold (p<0.05) and seven fold (p<0.05), respectively, in ImH.  CuZnSOD was elevated approximately 33% in Im and reduced in ImH (p<0.05).  Catalase was increased 10% (p<0.05) in the Im group compared to control and was similar to the ImH group.  Glutathione peroxidase tended to increase in the Im group and was 15% greater than in the ImH (p<0.05).  Glutathione reductase, and MnSOD did not differ between groups.  Based on these data we conclude that protection conveyed to muscle during immobilization through heating is not due to changes in native antioxidant enzymes and is likely due to changes in HSP expression.  

(Supported by the NFLPA Medical Charities)