Modulation of structural protein content of the myotendinous junction following eccentric contractions

The objective of this study was to test the hypothesis that vinculin acid t alin, two cytoskeletal proteins of the myotendinous junction (MTJ), would b e up-regulated following damaging eccentric contractions. Mouse plantarflex or muscles were submitted in situ to three 5 min periods of eccentric contr actions. Talin and vinculin content, in vitro contractile properties and MT J histology were examined at 0, 3, 7, 14, and 28 days post-exercise. The ec centric protocol led to significant decreases in maximum tetanic tension at 0, 3, and 7 days post-protocol. Histological examination did confirm that tissue damage was present at the MTJ where talin and vinculin are highly co ncentrated. In the type I soleus muscle talin content increased slightly at 7 days post-eccentric protocol compared to SHAM. In the type II piantaris muscle eccentric contraction led to an increase for vinculin and talin cont ents that was 2-3 fold higher than in the soleus; these significant changes were still present 28 days postexercise. These results show that eccentric contractions can trigger intense protein synthesis activity at the MTJ mos t likely related to myofibrillogenesis associated with MTJ remodeling.