Profiles of connectin (titin) in atrophied soleus muscle induced by unloading of rats
Profiles of connectin (titin) in atrophied soleus muscle induced by unloading of rats
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DOI：
10.1152/japplphysiol.00408.2002
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发表时间：
2003-03-01
影响因子：
3.3
通讯作者：
Yoshioka, T
中科院分区：
文献类型：
--
作者：
Goto, K;Okuyama, R;Yoshioka, T
本文研究了大鼠慢收缩比目鱼肌和快收缩趾长伸肌对3天的去负荷和3天的再负荷的反应。无负荷组Sol的湿重（相对于体重）显著低于年龄匹配的对照组（P < 0.05），而趾长伸肌的湿重则无显著性差异（P> 0.05）。免疫电镜分析表明，连接蛋白（SM 1）的单克隆抗体绑定到I带区域接近的边缘的A带在休息长度和可逆地移动远离Z线的肌纤维被拉伸。在溶胶中，位移的SM 1结合密集点在拉伸后后肢悬挂减少。后肢悬吊后两块肌肉中α-和β-连接蛋白的分子量和百分比分布没有变化。后肢悬吊后再负荷3d，Sol中β-connectin含量显著增加（P < 0.05）。这表明，在I-带区域的萎缩的溶胶纤维的连接蛋白丝的弹性相对于对照纤维减少。萎缩的肌纤维缺乏弹性可能导致收缩功能下降。
Responses of the properties of connectin molecules in the slow-twitch soleus (Sol) and fast-twitch extensor digitorum longus muscles of rats to 3 days of unloading with or without 3-day reloading were investigated. The wet weight (relative to body wt) of Sol, not of extensor digitorum longus, in the unloaded group was significantly less than in the age-matched control (P < 0.05). Immunoelectron microscopic analyses showed that a monoclonal antibody against connectin (SM1) bound to the I-band region close to the edge of the A band at resting length and moved reversibly away from the Z line as the muscle fibers were stretched. In Sol, the displacement of the SM1-bound dense spots in response to stretching decreased after hindlimb suspension. There were no changes in the molecular weights and the percent distributions of α- and β-connectin in both muscles after hindlimb suspension. A significant increment of percent β-connectin in Sol was observed after 3 days of reloading after hindlimb suspension (P < 0.05). It is suggested that the elasticity of connectin filaments in the I-band region of the atrophied Sol fibers was reduced relative to that of the control fibers. The lack of the elasticity in atrophied muscle fibers may cause a decrease in contractile function.