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This Article Full Text Full Text (PDF) All Versions of this Article: 93/3/415    most recent expphysiol.2007.041228v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Huey, K. A. Articles by Lullo, C. Search for Related Content PubMed PubMed Citation Articles by Huey, K. A. Articles by Lullo, C.

¹ Department of Kinesiology, University of Illinois, Urbana, IL, USA ² Brain Research Institute, University of California, Los Angeles, Box 951761, 1320 Gonda Neuroscience and Genetics Building, Los Angeles, CA, USA

Chronic reductions in muscle activation and loading are associated with decreased heat shock protein 25 (Hsp25) expression and phosphorylation (pHsp25) which, in turn, may contribute to elevated caspase-3-mediated muscle protein breakdown. Thus, the purpose of the present study was to determine whether there are any changes in Hsp25, pHsp25 and caspase-3 activity among rat muscles having different fibre type compositions and functions [soleus, adductor longus (AL), plantaris and tibialis anterior (TA)] at 0 (control), 1, 8 or 28 days after a complete spinal cord transection (ST). The Hsp25 levels were unaffected on days 1 and 8 in all muscles, except for a significant reduction on day 8 in plantaris. The Hsp25 levels were lower than control values in all muscles except TA on day 28. The pHsp25 levels were lower than control values after 8 and 28 days in plantaris and AL and after 28 days in soleus, but higher than control in TA after 8 and 28 days. Caspase-3 activity was higher in ST than control rats on day 8 in all muscles except TA. Caspase-3 activity was negatively correlated with muscle mass for all muscles. In plantaris, Hsp25 and pHsp25 were negatively correlated with caspase-3 activity and Hsp25 was correlated with muscle mass. These relationships were not observed in other muscles. Thus, the effects of ST on Hsp25 and caspase-3 are muscle specific and time dependent, factors that should be considered in developing any intervention to maintain muscle mass after a spinal cord injury.

(Received 26 October 2007; accepted after revision 17 December 2007; first published online 21 December 2007)
Corresponding author K. A. Huey: Department of Kinesiology, University of Illinois, Urbana-Champaign, 120 Freer Hall, 906 South Goodwin Avenue, Urbana, IL 61801, USA. Email: khuey{at}uiuc.edu