Big Load Movement And Recovery Of Rat Skeletal Muscle And Myocardial Ultrastructure And Related Repair Factor Changes

Objective:The purpose of this paper was to study the changes of skeletal muscle and cardiac muscle ultrasructure and to explore the changes of proliferating cell nuclear antigen and cardiotrophin-1during heavy load exercise and recovery in rat.Methods:36male SD rats of6weeks old were randomly divided in6groups,and each group had six rats.Control group(C) and after exhaustive exercise group (Exhaustive0,E0),12h group (E12),24h group (E24),48h group (E48),72h group (E72).The rats of exercise groups carrided on exhaustive loaded swimming every day for one weeks, and movement pattern of rat was tail-loaded swimming with the weight of3%of body weight. After the last exhaustive exercise at different time points,each rat was anesthetized intraperitoneally to slaughter with urethan,and tibialis anterior cardiac muscle were taken. Some were used for cryopreservation in Liquid nitrogen and the others were used to fix with2.5%glutaraldehyde.A part of tibialis anterior and cardiac muscle were fixed for producing ultrathin sections and observed the ultrastructural changes by transmission electron microscope.The other part of tibialis anterior was to measure the proliferating cell nuclear antigen by Western bolt, and some cardiac muscle was to measure cardiotrophin-1by Elisa.Result:1)By observing the electron micrographs of the tibialis anterior, we found a normal ultrastructure of skeletal muscle in the control group.The myofibril had intact structure,all kinds of bands were clearly and visible, the myofibril arranged regularly, The nucleus and mitochondria had intact structure, and their membranes had normal structure. However, the skeletal muscle structure in exhaustive exercise groups(E(E0、E24) were significantly damaged with the myofibril disorder and muscle gap widened, M lines and Z lines blurred, H band and I band took ill-defined, some mitochondrias were deformed, distorted and swollen.2)By observing the electron micrographs of the cardiac muscle, we found a normal ultrastructure of cardiac muscle in the control group.The control group of cardiac myofibril arranged regular. The cardiac myofibril had intact structure, and a lot of mitochondrias were distributed in the myofibril, many of mitochondria’s shape was round or oval. After exhaustive exercise, cardiac muscle ultrastructures had different changes in EO and E24. The myofibril disorder and sarcomere was within a wide range of fracture. Some mitochondrias were reduced and deformed、distorted.3)By Western blot to measure proliferating cell nuclear antigen(PCNA) of the tibialis anterior, after exhaustive exercise of one week, we found that PCNA contents in the tibialis anterio increased significantly in the exhaustive exercise groups compared with the quiet control group(P<0.05), especially,E24was increased siginificantly compared with E0(P<0.01).4)By ELISA to measure cardiotrophin-1(CT-1) of the cardiac muscle, we found that cardiotrophin-1(CT-1) increased after exhaustive exercise of cardiac muscle, Compared with the control group, the activity of CT-1in all exhaustive exercise groups(E(E0、E121、E24、E48、E72)had a significant improvement(P<0.01). Especially, EO was increased siginificantly compared with E72(P<0.01), and the cardiotrophin-1(CT-1) of the cardiac muscle clearly expressed at EO with a peak.Conclusion:1)The ultrastructure of skeletal muscle structure in exhaustive exercise groups were significantly damaged during heavy load exercise and recovery. The myofibril disorder and muscle gap widened, M lines and Z lines blurred, H band and I band took ill-defined. Some mitochondrias were deformed, distorted and swollen.2)The ultrastructure of cardiac muscle structure in exhaustive exercise groups were significantly damaged during heavy load exercise and recovery. The cardiac myofibril disorder and sarcomere was within a wide range of fracture. Some mitochondrias were reduced and deformed、distorted.3)The proliferating cell nuclear antigen(PCNA) of the tibialis anterior was increased after exhaustive exercise during heavy load exercise and recovery. PCNA expressed to a peak at E24, and it indicated that proliferating cell nuclear antigen can be accelerated the repair of soft tissue injury.4)The cardiotrophin-1(CT-1) was increased after exhaustive exercise of cardiac muscle during heavy load exercise and recovery.CT-1expressed to a peak at EO, and it indicated that cardiotrophin-1can be accelerated the repair of cardiac muscle injury.