Heat shock protein translocation and expression response is attenuated in response to repeated eccentric exercise.
OBJECTIVE
This study hypothesized that heat shock protein (HSP) translocation and upregulation is more probable to occur after eccentric exercise than after concentric exercise or repeated eccentric exercise.


METHODS
Fourteen young, healthy, untrained male subjects completed two bench-stepping exercise bouts with 8 weeks between bouts, and were compared with a control group (n = 6). Muscle biopsies collected from m. vastus lateralis of both legs prior to and at 3 h, 24 h and 7 days after exercise were quantified for mRNA levels and/or for HSP27, alphabeta-crystallin and inducible HSP70 content in cytosolic and cytoskeletal protein fractions.


RESULTS
The first bout of exercise reduced muscle strength and increased muscle soreness predominantly in the eccentric leg (P < 0.05). These responses were attenuated after the repeated eccentric exercise bout (P < 0.05), suggesting a repeated bout adaptation. Increases in inducible HSP70 and HSP27 protein content in cytoskeletal fractions were observed exclusively after eccentric exercise (P < 0.05). For HSP27, an approx. 10-fold upregulation after first-bout eccentric exercise was attenuated to a an approximately fourfold upregulation after the repeated eccentric exercise bout. mRNA levels for HSP70, HSP27 and alphabeta-crystallin were upregulated within approximately two to fourfold ranges at time points 3 and 24 h post-exercise (P < 0.05). This upregulation was induced exclusively by eccentric exercise but with a tendency to attenuated expression 3 h after the repeated eccentric exercise bout.


CONCLUSIONS
Our results show that HSP translocation and expression responses are induced by muscle damaging exercise, and suggest that such HSP responses are closely related to the extent of muscle damage.
Vissing
K
K
Department of Sport Science, University of Aarhus, Aarhus, Denmark. vissing@idraet.au.dk
Bayer
M L
ML
Overgaard
K
K
Schjerling
P
P
Raastad
T
T
D000328:Adult; D001706:Biopsy; D003402:Creatine Kinase / Q000097:blood; D003599:Cytoskeleton / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D015870:Gene Expression / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology*; D055551:HSP27 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007866:Leg / Q000473:pathology / Q000502:physiology; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000473:pathology / Q000502:physiology*; D009211:Myoglobin / Q000097:blood; D010147:Pain Measurement; D021381:Protein Transport; D015854:Up-Regulation / Q000235:genetics; D055815:Young Adult; D038201:alpha-Crystallins / Q000235:genetics; D038204:beta-Crystallins / Q000235:genetics
D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D009211:Myoglobin; D038201:alpha-Crystallins; D038204:beta-Crystallins; D003402:Creatine Kinase