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目的:探讨运动诱导的骨骼肌细胞凋亡和肌纤维类型百分构成的关系。方法:30只成年雄性SD大鼠随机分为安静对照组(不运动)、中等强度运动组(18m/min,100min)和大强度运动组(28m/min,20min),每组10只。安静组和运动组大鼠分别于安静状态和运动后即刻处死,取后肢腓肠肌内侧头,分别以原位末端标记法(TUNEL)测试细胞凋亡,ATP酶染色法鉴定Ⅰ型和Ⅱ型骨骼肌纤维,SDS-PAGE凝胶电泳分离肌凝蛋白重链(MHC),MHCⅠ、MHCⅡa、MHCⅡb和MHCⅡx。结果:(1)安静对照组大鼠腓肠肌内侧头仅检测到少量TUNEL阳染细胞核;中等强度运动组有散在的TUNEL阳染细胞核,凋亡指数为19.01±6.61;大强度运动组也检测到TUNEL阳染细胞核,凋亡指数为11.51±4.33%。(2)中等强度运动组细胞凋亡指数与Ⅱ型肌纤维面积百分比的相关系数r为0.776(P<0.05);大强度运动组细胞凋亡指数与Ⅱ型肌纤维面积百分比的相关系数r为0.737(P<0.05)。(3)中等强度运动组细胞凋亡指数与MHCⅡa亚型百分比呈高度正相关(r=0.787,P<0.05);与MHCⅡb亚型百分比呈低度负相关(r=-0.334,P<0.05);大强度运动组的结果与中等强度组基本一致。结论:运动量是影响骨骼肌细胞凋亡率的关键因素之一,肌细胞凋亡率在一定程度上随运动量的增加而升高,并且Ⅱ型肌纤维(快肌纤维)百分比高的骨骼肌在大强度和中等强度跑台运动中更易发生细胞凋亡。
Objective: To investigate the relationship between exercise-induced apoptosis of skeletal muscle cells and percentage of muscle fiber types. Methods: Thirty adult male Sprague-Dawley rats were randomly divided into 4 groups: control group (no exercise), moderate intensity exercise group (18m / min, 100min) and high intensity exercise group (28m / min, 20min) Rats in quiet group and exercise group were sacrificed in quiet state and immediately after exercise, respectively. The medial head of gastrocnemius muscle of hindlimb was taken and apoptosis was tested by TUNEL method. Type Ⅰ and Ⅱ skeletal muscle fibers were identified by ATPase staining , Myosin heavy chain (MHC), MHC I, MHC IIa, MHC IIb and MHC IIx were separated by SDS-PAGE gel electrophoresis. Results: (1) Only a few TUNEL-positive nuclei were detected in the medial head of the gastrocnemius muscle in the quiet control group; in the moderate-intensity exercise group, the apoptotic index was 19.01 ± 6.61 in the nuclei of scattered TUNEL-positive cells; TUNEL was also detected in the intensive exercise group The number of apoptotic nuclei was 11.51 ± 4.33%. (2) The correlation coefficient r was 0.776 (P <0.05) between the moderate intensity exercise group and the typeⅡ muscle fiber area percentage; the correlation coefficient r between the intensity exercise group and the typeⅡ muscle fiber area percentage was 0.737 P <0.05). (3) The apoptosis index of moderate-intensity exercise group was highly positively correlated with the percentage of MHCⅡa subtype (r = 0.787, P <0.05), and negatively correlated with the percentage of MHCⅡb subtype (r = -0.334, The result of intensive exercise group was basically the same as that of medium intensity group. Conclusion: The amount of exercise is one of the key factors that affect the apoptosis rate of skeletal muscle cells. The rate of myocyte apoptosis increased to a certain extent with the increase of exercise intensity, and skeletal muscle with high percentage of type Ⅱ myofibers (fast muscle fibers) And moderate-intensity treadmill exercise more prone to apoptosis.