一次性离心运动对大鼠骨骼肌骨架蛋白表达和肌力的影响

目的:探讨一次性离心运动对大鼠骨骼肌肌力和收缩蛋白myosin,细胞膜骨架蛋白dystrophin、a-DG、-DG,细胞外基质蛋白laminin-2、collagen IV表达的影响,以及上述蛋白与骨骼肌收缩力和拉断力的相关关系。方法:42只雄性Wistar大鼠分成对照组(n=6)和运动组(n=36)。运动组大鼠进行一次性离心运动,坡度为-16°,跑速为26.8 m/min,运动5 min,间歇1 min,共进行10组。分别于运动后即刻、4小时、24小时、48小时、72小时、7天,将大鼠腓肠肌在半离体状态下固定于微型材料实验机,用电刺激法测试大鼠腓肠肌收缩力,然后测拉断力,后取材测试血清CK、LDH,用免疫组化法测定大鼠腓肠肌myosin、dystrophin、-DG、-DG、laminin-2、collagen IV蛋白和laminin-2基因表达。结果:一次性离心运动后即刻,大鼠血清CK和LDH与对照组相比均有显著性增加(P<0.05)。一次性离心运动后即刻和48小时,大鼠腓肠肌收缩力与对照组相比显著下降(P<0.05),运动后24小时拉断力与对照组相比显著下降(P<0.05)。收缩力与拉断力呈正相关(r=0.501,P<0.01);一次性离心运动即刻laminin-2基因表达与对照组相比显著下降(P<0.05),运动后24小时laminin-2蛋白含量与对照组相比显著增加(P<0.05)。骨架蛋白含量与大鼠腓肠肌收缩力无相关关系,laminin-2蛋白含量变化与大鼠腓肠肌拉断力呈负相关(r=-0.727,P<0.01)。结论:(1)一次性离心运动致骨骼肌损伤,收缩力下降和肌肉损伤有关。(2)大鼠腓肠肌的材料力学特性在一次性离心运动后24小时最弱。(3)大鼠腓肠肌收缩力和骨架蛋白变化无相关关系。(4)大鼠腓肠肌拉断力在一次性离心运动后和laminin-2蛋白含量高度负相关,其内在机制值得进一步探讨。

Effect of Single Bout of Eccentric Exercise on the Expression of Cytoskeleton and Muscle Strength of Rats

Objective The present study investigated the changes in maximum contractile force,breaking load force and the expression of cytoskeleton protein of the skeletal muscle affected by single bout of acute eccentric exercise in rats.Methods Forty two male adult Wistar rats were divided randomly into 7 groups:one blank control group(n = 6),and six eccentric exercise groups:immediate group(n = 6),4-hour group(n = 6),24-hour group(n = 6),48-hour group(n = 6),72-hour group(n = 6),and 7-day group(n = 6).The rats in eccentric exercise groups ran on a treadmill at the speed of 26.8 m/min with a slope of-16°,5 min×10 times with an interval of 1 min.Sampling for eccentric exercise groups was carried out immediate,4 hours,24 hours,48 hours,72 hours and 7 days after modeling,respectively.The sampling time for blank control group was the same as the immediate group.Results After acute eccentric exercise,serum CK,LDH had significant increased as compared to the blank control group;significant change in the maximum contractile force of the gastrocnemius in immediate group and 48-hour group were found,as compared to the blank control group.Significant change in the breaking load force of the gastrocnemius in 24-hour group was appeared,as compared to the blank control group(P < 0.05).There was significant decrease in the laminin-2 gene levels of skeletal muscle in immediate group,as compared to the blank control group(P < 0.05) Expression of laminin-2 protein increased significantly in 24-hour group,as compared to the blank control group(P < 0.05).The expression of cytoskeleton did not correlate with the maximum contractile force of the gastrocnemius after acute eccentric exercise.The expression of laminin-2 protein was negatively correlated with the breaking load force of gastrocnemius(r = –0.727,P < 0.01).Conclusion(1)Single bout of eccentric exercise could cause muscle damage,resulting in the loss of muscle strength.(2)The mechanical property of skeletal muscle of rats weakened the most at 24 hours after acute eccentric exercise.(3)The expression of cytoskeleton did not correlate with the maximum contractile force of the gastrocnemius after acute eccentric exercise.(4)There was a high negative correlation between the breaking load force and the expression of laminin-2.