Effects of muscle length on the response to unloading.

Acta anatomica Pub Date : 1997-01-01 DOI:10.1159/000147971
Y Ohira, W Yasui, R R Roy, V R Edgerton
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引用次数: 29

Abstract

Muscle mass, distribution of fiber types, fiber cross-sectional areas (CSA) and selected enzyme activities were determined in rats hindlimb-suspended free of immobilization (Susp-Free), suspended with the ankle dorsiflexed (Susp-DF, soleus stretched) or plantarflexed (Susp-PF, soleus shortened) for 10 days and compared to cage-control (Con) rats. Reduction of muscle weight associated with suspension was prevented in Susp-DF rats. The mean CSAs of slow fibers were Con = Susp-DF > Susp > PF > Susp-Free and of fast and intermediate fiber tended to be Susp-DF > Con > Susp-PF = Susp-Free. Mean activities of succinate dehydrogenase (SDH), alpha-glycerophosphate dehydrogenase (GPD) and myofibrillar adenosine triphosphatase (mATPase) in slow and fast fibers were similar in Con and Susp-Free rats. Mean SDH activity in slow fibers was higher in Susp-DF and Susp-PF than in Con and Susp-Free. No significant differences in SDH activities of fast fibers were observed among groups. GPD activity was higher in slow fibers of Susp-DF and Susp-PF compared to Con. The mATPase activity was higher in slow fibers of Susp-DF compared to Con and Susp-Free rats and lower in fast fibers of Susp-DF compared to Con rats. Thus, when compared to control, the patterns of adaptation were more similar in the Susp-DF and Susp-PF than in the Susp-Free. Although these results are consistent with previous studies demonstrating that the load placed on a muscle can affect protein metabolism, the direction and magnitude of the adaptive responses observed in the present study were closely associated with the chronically imposed changes in muscle length, i.e. fixed at either a shortened or a lengthened position.

肌肉长度对卸荷反应的影响。
测定大鼠后肢悬吊不固定(suspend - free)、踝关节背屈(suspend - df,拉伸比目鱼肌)或跖屈(suspend - pf,缩短比目鱼肌)10天的肌肉质量、纤维类型分布、纤维横截面积(CSA)和选定酶活性。在悬浮- df大鼠中,肌肉重量的减少与悬浮有关。慢纤维的平均csa为Con = suspend - df > Susp > PF > Susp- free,快纤维和中间纤维的平均csa为suspend - df > Con > suspend -PF = Susp- free。Con和free大鼠慢纤维和快纤维中琥珀酸脱氢酶(SDH)、α -甘油磷酸脱氢酶(GPD)和肌纤维腺苷三磷酸酶(mATPase)的平均活性相似。悬浮- df和悬浮- pf组慢纤维SDH平均活性高于Con和free组。各组间快纤维SDH活性无显著差异。与对照组相比,悬浮- df和悬浮- pf的慢纤维中GPD活性更高。悬浮- df的慢纤维中mATPase活性高于对照组和无悬浮大鼠,悬浮- df的快纤维中mATPase活性低于对照组。因此,与对照相比,悬架- df和悬架- pf的适应模式比悬架- free更相似。虽然这些结果与先前的研究一致,表明施加在肌肉上的负荷可以影响蛋白质代谢,但本研究中观察到的适应性反应的方向和幅度与长期施加的肌肉长度变化密切相关,即固定在缩短或延长的位置。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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