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目的探讨间断性 45°头高位倾斜 (HUT)能否减轻或防止模拟失重大鼠后肢骨骼肌的萎缩性变化。方法将SD大鼠按体重匹配的原则随机分为同步对照 (CON)、模拟失重 (SUS)和模拟失重每日 6h+45°头高位倾斜 (SUS +HUT) 3组。 4wk后 ,取大鼠比目鱼肌 (SOL)、腓肠肌内侧头 (MG)及外侧头(LG)与趾长伸肌 (EDL) ,并称其湿重。采用组织酶化学染色及计算机图像分析技术对骨骼肌Ⅰ、Ⅱ型肌纤维横截面积 (CSA)、比例 ,及毛细血管与肌纤维数的比值 (C/F)进行定量分析。结果与CON相比 ,SUS大鼠后肢骨骼肌的湿重均显著减少 ,但各骨骼肌变化程度不一致。所有骨骼肌的C/F比值均显著降低。SUS +HUT组的变化如下 :①肌肉湿重 ,SOL完全恢复 ,MG +LG部分恢复 ;间断HUT对抗肌萎缩的相对对抗效果分别为 93.4%及 34.8%。②骨骼肌Ⅰ、Ⅱ型肌纤维CSA及比例 ,SOL完全恢复 ,MG部分恢复 ,其余骨骼肌仅有恢复趋势。③所有骨骼肌的C/F比值均得到恢复。结论本项研究表明间断HUT性能有效地对抗模拟失重所引起的后肢骨骼肌萎缩性变化 ,但不同骨骼肌的反应尚存在一定差异。本工作提示 ,应用间断性人工重力对抗失重不利影响的同时 ,尚应辅以其他对抗措施。
Objective To investigate whether discontinuity of 45 ° head tilt (HUT) can reduce or prevent atrophic changes of hindlimb skeletal muscle in simulated weightless rats. Methods SD rats were randomly divided into three groups: control group (CON), simulated weightlessness (SUS) and simulated weightlessness (HR + HUT). After 4 weeks, the soleus muscle (SOL), medial gastrocnemius (MG), lateral head (LG) and extensor digitorum longus (EDL) were harvested and weighed and their wet weights were obtained. The histochemical staining and computer image analysis were used to quantitatively analyze the muscle fiber cross-sectional area (CSA), ratio, and capillary / muscle fiber ratio (C / F) of skeletal muscle. Results Compared with CON, the wet weight of hindlimb skeletal muscle in SUS rats was significantly decreased, but the skeletal muscle changes were inconsistent. All skeletal muscle C / F ratios were significantly reduced. The changes of SUS + HUT group were as follows: (1) Muscle wet weight, SOL completely recovered and MG + LG partially recovered; the relative confrontation effect of intermittent HUT on muscle atrophy was 93.4% and 34.8% respectively. ② CSA and ratio of skeletal muscle type I and type II myocytes, SOL completely recovered, MG partially recovered, and the rest of skeletal muscle showed only a recovery trend. ③ All skeletal muscle C / F ratio were restored. Conclusions This study shows that intermittent HUT performance is effective against hindlimb skeletal muscle atrophy caused by simulated weight loss, but there are some differences in skeletal muscle response. This work suggests that intermittent artificial gravity should be used together with other countermeasures while countering the adverse effects of weightlessness.