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J Appl Physiol 107: 570-582, 2009. First published June 4, 2009; doi:10.1152/japplphysiol.00209.2009
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Subcellular movement and expression of HSP27, {alpha}B-crystallin, and HSP70 after two bouts of eccentric exercise in humans

G. Paulsen,1 F. Lauritzen,1,2 M. L. Bayer,1,3 J. M. Kalhovde,1 I. Ugelstad,1 S. G. Owe,2 J. Hallén,1 L. H. Bergersen,2 and T. Raastad1

1Norwegian School of Sport Sciences, Oslo, Norway; 2Department of Anatomy, University of Oslo, Oslo, Norway; and 3Institute of Sports Medicine, Bispebjerg Hospital, Copenhagen, Denmark

Submitted 24 February 2009 ; accepted in final form 28 May 2009

The aims of this study were to investigate the sarcomeric accumulation and expression of heat shock proteins (HSPs) after two bouts of maximal eccentric exercise. Twenty-four subjects performed two bouts of 70 maximal voluntary eccentric actions using the elbow flexors in one arm. The bouts were separated by 3 wk. The changes in concentric (60°/s) and isometric (90°) force-generating capacity were monitored for 9 days after each bout, and biopsies were taken 1 and 48 h and 4 and 7 days after bout 1 and 1 and 48 h after bout 2. The content of HSP27, {alpha}B-crystallin, HSP70, and desmin in the cytosolic and cytoskeleton/myofibrillar fractions of homogenized muscle samples was determined by immunoassays, and the cellular and subcellular localization of the HSPs in the myofibrillar structure was analyzed by conventional and confocal immunofluorescence microscopy and quantitative electron microscopy. The force-generating capacity was reduced by ~50% and did not recover completely during the 3 wk following bout 1. After bout 2, the subjects recovered within 4 days. The HSP levels increased in the cytosolic fraction after bout 1, especially HSP70 (~300% 2–7 days after exercise). Increased levels of HSP27, {alpha}B-crystallin, and HSP70 were found in the cytoskeletal/myofibrillar fraction after both bouts, despite reduced damage after bout 2. At the ultrastructural level, HSP27 and {alpha}B-crystallin accumulated in Z-disks, in intermediate desmin-like structures ({alpha}B-crystallin), and in areas of myofibrillar disruption. In conclusion, HSP27 and {alpha}B-crystallin accumulated in myofibrillar structures, especially in the Z-disks and the intermediate structures (desmin). The function of the small HSPs is possibly to stabilize and protect the myofibrillar structures during and after unaccustomed eccentric exercise. The large amount of HSP27, {alpha}B-crystallin, and HSP70 in the cytoskeletal/myofibrillar fraction after a repeated bout of exercise suggests a protective role as part of the repeated-bout effect.

muscle damage; stress proteins; desmin; quantitative immunogold analysis; electron microscopy


Address for reprint requests and other correspondence: G. Paulsen, Norwegian School of Sport Sciences, P.O. Box 4014 U.S., N-0806 Oslo, Norway (e-mail: goran.paulsen{at}nih.no)






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