title: Alterations in the expression and activity of creatine kinase-M and mitochondrial creatine kinase subunits in skeletal muscle following prolonged intense exercise in rats.
abstract: Creatine kinase (CK) isoenzymes are important structural and energy metabolism components in skeletal muscle. In this study, CK isoenzyme alterations were examined in male rats, with an 8% body mass weight attached to their tail. The rats were either forced to swim for 5 h (5S, n = 51), or were pre-trained for 8 days and then forced to swim for 5 h (T5S, n = 48). Rats were sacrificed either immediately (0 h PS), 3 h (3 h PS), or 48 h post-swimming (48 h PS). Serum CK was increased significantly (P < 0.01) 6.2- and 2.0-fold at 0 h PS following the 5S and T5S protocols, respectively. However, training (T5S protocol) significantly (P < 0.01) decreased CK release. Soleus and white gastrocnemius (WG) CK activity was significantly decreased following the 5S protocol (P < 0.05), but not following the T5S protocol. The CK-M activity of the soleus muscle was significantly (P < 0.05) decreased at 0 h PS following both the 5S and T5S protocols, and returned to control values at 3 h PS. The CK-M activity of the WG was significantly (P < 0.05) decreased at 0 h PS following the 5S protocol. Sarcomeric mitochondrial CK (sCK-Mit) was decreased significantly (P < 0.01) at 0 h PS (20%), 3 h PS (14%), 24 h PS (22%), and 48 h PS (15%) following the 5S protocol. However, sCK-Mit was decreased significantly (P < 0.01) only at 0 h PS (7%) following the T5S. The results of this study demonstrate that prolonged intense exercise causes a loss of skeletal muscle CK-M and sCK-Mit activity and that training prior to the prolonged intense exercise attenuates the exercise-induced CK-M and sCK-Mit loss in both red and white skeletal muscles.
authors.affiliation: Division of Kinesiology, School of Kinesiology and Leisure Studies, University of Minnesota, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.forename: R C
authors.initials: RC
authors.lastname: Serfass
authors.forename: F S
authors.initials: FS
authors.lastname: Apple
mesh_terms: D000818:Animals; D003402:Creatine Kinase / Q000097:blood / Q000378:metabolism*; D007527:Isoenzymes; D008297:Male; D008931:Mitochondria, Muscle / Q000201:enzymology*; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012518:Sarcomeres / Q000201:enzymology; D013550:Swimming; D013997:Time Factors
chemical_list: D007527:Isoenzymes; D003402:Creatine Kinase