A non-cross-bridge, static tension is present in permeabilized skeletal muscle fibers after active force inhibition or actin extraction
A non-cross-bridge, static tension is present in permeabilized skeletal muscle fibers after active force inhibition or actin extraction
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DOI：
10.1152/ajpcell.00355.2011
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发表时间：
2012-02-01
影响因子：
5.5
通讯作者：
Rassier, Dilson E.
中科院分区：
文献类型：
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作者：
Cornachione, Anabelle S.;Rassier, Dilson E.
角果为，Rassier de.在主动力抑制或肌动蛋白提取后，通透性骨骼肌纤维中存在一种非跨桥的静态张力。Am J Physiol Cell Physiol 302：C566-C574,2012。2011年11月16日首次出版；doi：10.1152/ajpcell.00355.2011。-当激活的肌肉纤维被拉伸时，力量会长期增加。这种现象被称为“残余力增强”，具有类似于“静态张力”的特征，“静态张力”是指在有钙离子存在但没有肌球蛋白-肌动蛋白相互作用的情况下，肌肉被拉伸时所观察到的持久的力量增加。独立的研究表明，这两种现象有一个共同的机制，要么是由于1)钙离子诱导的肌动蛋白硬化，要么是由于促进了肌动蛋白与肌动蛋白的结合。在这项研究中，我们进行了两组实验，用肌球蛋白抑制剂Blebbistatin处理的激活纤维(PCA(2+)4.5)以40 L/S的速度从2.7微米拉伸到2.8微米，第一组是在部分提取抑制肌球蛋白-肌动蛋白相互作用的TNC之后，第二组是用明胶处理后，导致细丝(肌动蛋白)的耗尽。我们观察到，在抑制肌球蛋白-肌动蛋白相互作用或耗尽肌钙蛋白C和肌动蛋白细丝纤维的处理后，与残余力增强直接相关的静态张力没有改变。结果表明，残余力的增强是由于肌动时肌动蛋白的僵硬，而不是肌动蛋白与肌动蛋白的结合。这一发现表明，骨骼肌中存在一种受钙离子调节的、基于肌动蛋白的僵硬。
Cornachione AS, Rassier DE. A non-cross-bridge, static tension is present in permeabilized skeletal muscle fibers after active force inhibition or actin extraction. Am J Physiol Cell Physiol 302: C566-C574, 2012. First published November 16, 2011; doi: 10.1152/ajpcell.00355.2011.-When activated muscle fibers are stretched, there is a long-lasting increase in the force. This phenomenon, referred to as "residual force enhancement," has characteristics similar to those of the " static tension," a long-lasting increase in force observed when muscles are stretched in the presence of Ca2+ but in the absence of myosin-actin interaction. Independent studies have suggested that these two phenomena have a common mechanism and are caused either by 1) a Ca2+-induced stiffening of titin or by 2) promoting titin binding to actin. In this study, we performed two sets of experiments in which activated fibers (pCa(2+) 4.5) treated with the myosin inhibitor blebbistatin were stretched from 2.7 to 2.8 mu m at a speed of 40 L-o/s, first, after partial extraction of TnC, which inhibits myosin-actin interactions, or, second, after treatment with gelsolin, which leads to the depletion of thin (actin) filaments. We observed that the static tension, directly related with the residual force enhancement, was not changed after treatments that inhibit myosin-actin interactions or that deplete fibers from troponin C and actin filaments. The results suggest that the residual force enhancement is caused by a stiffening of titin upon muscle activation but not with titin binding to actin. This finding indicates the existence of a Ca2+-regulated, titin-based stiffness in skeletal muscles.