The Change Of The Extracellar Matrix Content And Maximum Force Of The Skeletal Muscle Affected By Eccentric Exercise

1 PurposeThe purpose of this study was to investigate the change of the maximum force of the gastrocnemius affected by Eccentric Exercise and physical endurance training. The change of the contents of the cytoskeleton protein affected by Eccentric Exercise and physical endurance training.To analyse the relationship among the maximum force of the gastrocnemius and the loss of the cytoskeleton protein and the change of the serum enzyme after the exercise induced the muscle injury.To continue discuss the function of the cytoskeleton protein in skeleton muscle fibre.2 Experimental MethodsMale Wistar rats, weighing 300-360g, were performed an acute eccentric exercise and 6 weeks eccentric training. The acute eccentric exercise was -16°incline running on the treadmill at a speed of 26.8m/min, 5min×10groups with 1min rest. 6-wk training involves the 5days/wk, and the speed from 20.0m/min in the first week to 35.0m/min in the last three weeks, and the grade was always -5°. The tissues were collected from the gastrocnemius muscle of the experimental rats.The rat's foot was secured to a plate attached to a Miniature Materials Tester (model MiniMAT2000; made in USA). The bone was dissected free through a small incision and clamped with a stimulator (Nokion made in Japan) that was used to stimulate the gastrocnemius with a supramaximal tetanic current (75-Hz 50V). We used this stimulation intensity to activate the gastrocnemius in our experiments to induce maximal contractile activation then breaking load until gastrocnemius was snapped. Our protocol used commercial software (MiniMAT) to independently control the onset of contractile activation, proper velocity, and motion during plantar flexionTransverse muscle sections (15μm ) were cut at -20℃. Muscle fiber typing was diagnosed using metachromatic dye-ATPase methods. Laminin-2 content was determined by immunohistologically stain and Western blotting methods. The expression of Laminin-2 gene was detected by in situ hybridization with oligo nucleotide probe, digoxigenin labeled. Images acquired from stained sections were analyzed with Scion Image. CK, LDH in serum, SOD, MDA in muscular tissue were measured respectively. 3 Results3.1 The laminin-2 expression kept maximum level at 24 hour after eccentric exercise,quantitative analysis showed that laminin-2 protein content were significantly different in 24h and at a moment,48h,72h after eccentric exercise (P<0.05) ; The expression of collagenIV showed drop trendency after eccentric exercise .there had significantly different in 48h and 72h after eccentric exercise with controls(P<0.05); The a-DG exhibited lower relative content at a moment to 72hour after eccentric exercise,. there had significantly different with controls;. There exhibited positive remarkable relationship between the content of ECM collagenIV and serum CK, the content of a-DG and serum LDH; There also exhibited negative remarkable relationship between muscle SOD and serum LDH, serum Hydroxyproline and serum LDH; There not exhibit remarkable relationship between serum Hydroxyproline and the content of ECM collagenIV;3.2 The expression of laminin-2 gene reduced to 52% of sedentary level just after eccentric exercise (P<0.05), then increased to 142% of sedentary level at 4h then keep this level to 72h;3.3 The contractile force was reduced at a moment and 48h after eccentric exercise and exhibited significantly different with controls(P<0.05);The breaking load increased gradually at 4h then reduced at 24h after eccentric exercise,there exhibited significantly different between 24h after eccentric exercise and controls; There exhibit remarkable relationship between contractile force and the breaking load,there still exhibit the different trendency of the contractile force and the breaking load after eccentric exercise;3.4 There not exhibit remarkable relationship between muscle force and freedom ion metabolic, serum CK,LDH,Hydroxyproline ; There exhibited negative remarkable relationship between the content of Laminin-2 and the breaking load of the rat's gastrocnemius;There also exhibited positive remarkable relationship between the content of myosin and the content of collagenIV,a-DG;4 Conclusions4.1. The laminin-2 protein content, collagenIV protein content,a-DG protein content was influenced by eccentric exercise; There exhibited negative remarkable relationship between the content of laminin-2 and the breaking load of the rat's gastrocnemius;There also exhibited positive remarkable relationship between the content of myosin and the content of collagenIV,a-DG; There exhibit remarkable relationship between contractile force and the breaking load,there still exhibit the different trendency of the contractile force and the breaking load after eccentric exercise;4.2 There exhibited positive remarkable relationship between the content of ECM collagenIV and serum CK, the content of a-DG and serum LDH; There also exhibited negative remarkable relationship between muscle SOD and serum LDH, serum Hydroxyproline and serum LDH;4.3The change of the myosin's concentration depends on the different training ways,the same intensity of the eccentric endurance training could decrease the content of the myosin but increase the content of the laminin-2 ; the different intensity of the eccentric endurance training could increase the content of the myosin;4.4 The different intensity of the eccentric endurance training could increase contractile force and the breaking load;The same intensity of the eccentric endurance training could decrease contractile force and the breaking load;...