The Biological Study Of The Rats’ Skeletal Muscle Injury After Exhaustion With Moderate Intensity Exercise In Different Training Cycle

Objective:From the angle of skeletal muscle morphology and intracellular metabolic changes（LDH、ATP）,in contrast to the 31P-MRS, this study explored the characteristics and laws of rat`s change of skeletal muscle induced by moderate exercise and different cycles. 31P-MRS,with the results tested by the traditional detecting methods, has become a brand new way of detecting, which causes no injury and can be used for evaluating skeletal muscle injury.To evaluate the metabolic change in 31P-MRS in skeletal muscle of wistar mince after exhaustive exercise .providing a theoretical and experimental basis for the prevention and treatment of exercise-induced muscle damage（EIMD）.Methods:Matured wistar male rats were selected as the subjects of this study.Forty-eight health male rats were randomly and equally divided in 3 groups:2 weeks moderate exercise exhausted group（2WME, n=16）, 4 weeks moderate exercise exhausted group（4WME, n=16）, 6 weeks moderate exercise exhausted group（6WME, n=16）.The EIMD model was established by taking a bout of running.The brachii quadriceps femoris muscles were extracted from the right side of rats.Some were made into electron microscope slices and biochemical environment detectio.The others were made into 31P-MRS determination.Results:（1） The changes of injury structure were seriously most in 2 WME group after exhaustive exercise in skeletal muscle.Electron microscope showed that myofibrils with irregular arranges,part of Z-line with zigzag changes,Z-line streaming or Z lines disappearance and mitochondria`s vacuole degeneration or defects;There was no significant difference between 2WME and 4WME group. The damage of skeletal muscle ultrastructure of 6WME group was light. （2）There was no significant difference in the LDH and Na⁺—ATP level of between 2WME and 4WME group in muscle tissue,but the LDH and Na⁺—ATPlevel of 6WME group was significant higher than 2WME and 4WME group（P<0.01）. There was significant difference in the Ca²⁺,Mg²⁺—ATP level of between 2WME and 4WME group in muscle tissue（P<0.01）.The Ca²⁺,Mg²⁺—ATP level of 6WME group was significantly higher than 2WME and 4WME group（P<0.01）.（3） )There was no significant difference in the peak area of Pi、PCr、β-ATP of between 2WME and 4WME group,but the of peak area of Pi、PCr、β-ATP 6WME group was significant higher than 2WME group（P<0.05）. There was no significant difference in the the ration of Pi/β-ATP between 2WME and 4WME group , The ration of Pi/β-ATP of 6WME group was significant higher than 2WME group（P<0.05）Conclusions:The changes of injury structure were seriously most in 2WME after exhaustive exercise in skeletal muscle.Exhaustive exercise could cause the change of electron microscopy structure.At least for six weeks moderate exercise induce repeted bout effect（RBE）. 31P-MRS could quatitatively reflect the wistar mice exercise-induced injury after exhaustive exercise,the peak area of Pi、PCr、ATP which could evaluate the degree of injury .The ratio of Pi/ATPwhich could evaluate the degree of injury ,also be .taken as indexes of exercise-induced injury.