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TRANSFORMING GROWTH FACTOR-β IN SKELETAL MUSCLE STRAIN INJURY

Smith, C A.1; Stauber, FACSM, W T.1; Alway, FACSM, S E.1; Miller, G R.1

Medicine & Science in Sports & Exercise: May 2001 - Volume 33 - Issue 5 - p S230
F19D FREE COMMUNICATION/SLIDE MOLECULAR AND GENETIC ASPECTS OF PERFORMANCE
Free

1West Virginia University, Morgantown, WV

The presence of transforming growth factor-β (TGF-β) in skeletal muscle has been reported in various muscle disease. In this study, we assess the presence of transforming growth factor-β in strain-induced muscle injury. Muscle strains were produced by manually stretching (50 repetitions) an activated plantar flexor group through its normal range of motion. Muscle biopsy samples were evaluated 24- and 48- hours after strain injury for the presence of transforming growth factor-β using immunohistochemical techniques and Western immunoblot analysis. Transcript levels for collagen I, collagen III, and transforming growth factor-β were assessed using reverse transcriptase polymerase chain reaction (RT-PCR). Immunohistochemical analysis revealed the presence of TGF-β2 in areas of myofiber injury, whereas TGF-β1 was in areas of cell necrosis and phagocytosis. RT-PCR indicated increases in collagen I, collagen III, and TGF-β1 transcripts 24 hours post-strain injury. Increases in collagen I and collagen III transcripts were more pronounced 48 hours after strain injury. Western immunoblot analysis showed no apparent change in TGF-β2 levels with injury, but an increase in TGF-β1 levels which was most pronounced 48 hours post-strain injury. These results indicate that TGF-β1 levels increase after acute strain injury following increases in TGF-β1 mRNA correlating with increases in collagen I and collagen III transcripts, whereas TGF-β2 may be a common resident in skeletal muscle awaiting activation. Supported by NIOSH R01-OH-02918 and AG 17143-01

©2001The American College of Sports Medicine