title: Cathepsin D and MMP-9 activity increase following a high intensity exercise in hind limb muscles of young rats.
abstract: 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(-1) gradually 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(-3) to 10.7 x 10(-3) or 61% nM tyrosine x mg-1 protein x min-1) and the soleus (from 5.9 x 10(-3) to 8.9 x 10(-3) or 66%). The activity level of mRNA MMP-9, expressed as ng mg(-1) protein, 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.
authors.affiliation: Department of Physical Therapy, Sackler Faculty of Medicine, The Stanley Steyer School of Health Professions, Tel Aviv University, Ramat Aviv, Israel. elie@post.tau.ac.il
authors.forename: Eli
authors.initials: E
authors.lastname: Carmeli
authors.forename: Tal
authors.initials: T
authors.lastname: Haimovitz
authors.forename: E Carlos
authors.initials: EC
authors.lastname: Nemcovsky
mesh_terms: D000818:Animals; D002402:Cathepsin D / Q000096:biosynthesis*; D005260:Female; D006614:Hindlimb; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis*; D018485:Muscle Fibers, Skeletal / Q000201:enzymology; D018482:Muscle, Skeletal / Q000201:enzymology*; D010805:Physical Conditioning, Animal; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002402:Cathepsin D; D020780:Matrix Metalloproteinase 9