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This Article Full Text Full Text (PDF) All Versions of this Article: 293/2/R844    most recent 00677.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Paulsen, G. Articles by Raastad, T. Search for Related Content PubMed PubMed Citation Articles by Paulsen, G. Articles by Raastad, T.

ENVIRONMENTAL, EXERCISE AND RESPIRATORY PHYSIOLOGY

Maximal eccentric exercise induces a rapid accumulation of small heat shock proteins on myofibrils and a delayed HSP70 response in humans

¹Norwegian School of Sport Sciences, Oslo, Norway; ²Department of Sports Science, Aarhus University, Aarhus; ³Department of Molecular Muscle Biology, Copenhagen Muscle Research Centre, Rigshospitalet, Copenhagen; ⁵Department of Medical Biochemistry and Genetics, University of Copenhagen, Copenhagen, Denmark; and ⁴Department of Physical Education and Health, Örebro University, Örebro, Sweden

Submitted 25 September 2006 ; accepted in final form 18 May 2007

In this study the stress protein response to unaccustomed maximal eccentric exercise in humans was investigated. Eleven healthy males performed 300 maximal eccentric actions with the quadriceps muscle. Biopsies from vastus lateralis were collected at 30 min and 4, 8, 24, 96, and 168 h after exercise. Cellular regulation and localization of heat shock protein (HSP) 27, B-crystallin, and HSP70 were analyzed by immunohistochemistry, ELISA technique, and Western blotting. Additionally, mRNA levels of HSP27, B-crystallin, and HSP70 were quantified by Northern blotting. After exercise (30 min), 81 ± 8% of the myofibers showed strong HSP27 staining (P < 0.01) that gradually decreased during the following week. B-Crystallin mimicked the changes observed in HSP27. After exercise (30 min), the ELISA analysis showed a 49 ± 13% reduction of the HSP27 level in the cytosolic fraction (P < 0.01), whereas Western blotting revealed a 15-fold increase of the HSP27 level in the myofibrillar fraction (P < 0.01). The cytosolic HSP70 level increased to 203 ± 37% of the control level 24 h after exercise (P < 0.05). After 4 days, myofibrillar-bound HSP70 had increased 10-fold (P < 0.01) and was accompanied by strong staining on cross sections. mRNA levels of HSP27, B-crystallin, and HSP70 were all elevated the first day after exercise (P < 0.01); HSP70 mRNA showed the largest increase (20-fold at 8 h). HSP27 and B-crystallin seemed to respond immediately to maximal eccentric exercise by binding to cytoskeletal/myofibrillar proteins, probably to function as stabilizers of disrupted myofibrillar structures. Later, mRNA and total HSP protein levels, especially HSP70, increased, indicating that HSPs play a role in skeletal muscle recovery and remodeling/adaptation processes to high-force exercise.

stress proteins; muscle damage; eccentric actions; skeletal muscle