Fig. 3

Matrix metalloproteinase (MMP)-3 levels increase whereas MMP-13 decreases in flexor digitorum muscles with high repetition negligible force (HRNF) task. a Representative Western blot of muscle homogenates probed with MMP-3. Bands are at the expected molecular weights of latent and active forms of MMP-3 (approximately 57–59, 45, and 28 kDa). β-actin was used as a loading control. b-d Densitometric analysis of latent (57–59 kDa) and active (45 and 28 kDa) bands of MMP-3 from three replicate Western blots were normalized to β-actin levels. e A representative Western blot of muscle homogenates probed with MMP-13. Doublet bands observed at the expected molecular weight of active MMP-13 (approximately 48 kDa) were analyzed, averaged and normalized to the loading control. f Densitometric analysis of active (48 kDa) form of MMP-13 from three replicate Western blots after normalization to β-actin levels shows that it decreased significantly with the HRNF task. *p < 0.05, **p < 0.01, compared to FRC rats; ns = not significant