肌肉拉伸对去负荷比目鱼肌Z线结构的保护作用研究

Stretch of Muscle Preserves Z-disc Structure in Unloaded Soleus

目的探寻在骨骼肌去负荷过程中,能够防止Z线改变的对抗措施。方法将大鼠分为对照组(Con)、对照拉伸组(Con+stretch)、悬吊组(TS)和悬吊拉伸组(TS+stretch)4组,对照拉伸组及悬吊拉伸组在对照及悬吊基础上采用石膏固定方法将踝关节固定于背屈位。每组10只大鼠,共计40只。观测比目鱼肌湿重与其肌纤维超微结构的变化。结果与对照组相比,对照拉伸组比目鱼肌重量/体重比明显降低,悬吊组进一步下降;悬吊拉伸组明显高于去负荷组。对照拉伸组比目鱼肌肌纤维超微结构未见明显改变,定量观测表明肌节长度、A带与I带宽度均无显著性改变,肌原纤维与Z线宽度呈降低趋势。TS组Z线呈波浪样改变,肌原纤维与Z线宽度呈显著性缩窄。悬吊拉伸组肌节结构基本正常,肌原纤维与Z线宽度呈降低趋势。结论适当拉伸比目鱼肌可部分阻止去负荷导致的肌肉萎缩,并能防止Z线结构的损伤性改变。

Objective To explore the effects of passive stretch on preserving Z-disc structure in unloaded soleus muscle Methods Forty rats were equally divided to control（Con）,control with stretch（Con ＋ stretch）,tail-suspension（TS） and tail-suspension with stretch（TS＋stretch）.The tail-suspended rat model was used to induce an unloading of soleus muscle for 2 weeks.Left ankle of rat was fixed by a plaster cast at 35° of dorsiflexion.The soleus muscle was passively stretched in the fixed hind-limb.The changes of wet weight and ultrastructure of soleus muscle were examined.Results Compared with Con group,the ratio of soleus wet weight to body weight was decreased in the stretched muscle of Con＋stretch group;the relative weight of soleus was further decreased in TS group.The decrease in the relative weight of soleus was partially reversed in the stretched muscle of TS＋stretch group.The width of myofibril and Z-disc showed a trend toward reduction in soleus fibers of Con＋stretch group and decreased significantly in TS group as compared with the Con group.The lengths of sarcomere and I-band were increased,but the length of A-band was unaltered in the TS group.The Z-disc showed a wavy appearance in TS group.Passive stretch in the unloaded soleus muscle restored normal appearance of Z-disc.The lengths of sarcomere,I-band,and A-band were unaltered.The widths of myofibril and Z-disc were also preserved at the levels of control soleus muscle.Conclusion These results indicate that passive stretch can prevent partially atrophy and preserve the Z-disc structure in the unloaded soleus muscle.