The influence of an intensive exercise regime on cathepsin D and MMP-9 activity in hind limb muscles was investigated. We hypothesized that high-intensity exercise would increase the number of these proteins, indicating their involvement in the pathogenesis of exercise-induced muscle injury. Muscle fibers from the gastrocnemius and soleus were used from young (6-mo-old) female rats (n = 6) who completed 10 consecutive days of treadmill running at high intensity (34 m min-1gradually up to 40 min per day), compared with nonrunning, age and sex-matched rats (n = 6). After a high-intensity exercise regime, cathepsin D activity significantly increased in the gastrocnemius (from 6.6 x 10-3to 10.7 x 10-3or 61% nM tyrosine x mg protein x min-1) and the soleus (from 5.9 x 10-3to 8.9 x 10-3or 66%). The activity level of mRNA MMP-9, expressed as ng mg-1protein, increased in both muscles subjected to intensity running. The results of this study suggest that high-intensity running results in an elevation in the activity of lysosomal enzymes involved in matrix protein degradation.
|Number of pages||8|
|Journal||Journal of Basic and Clinical Physiology and Pharmacology|
|State||Published - 2007|
ASJC Scopus subject areas
- Drug Discovery