Adjustable passive length-tension curve in rabbit detrusor smooth muscle.
Adjustable passive length-tension curve in rabbit detrusor smooth muscle.
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兔逼尿肌平滑肌的可调节被动长度张力曲线。
DOI：
10.1152/japplphysiol.00548.2006
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Ratz,PaulH
中科院分区：
文献类型：
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作者：
Speich,JohnE;Dosier,Christopher;Borgsmiller,Lindsey;Quintero,Kevin;Koo,HarryP;Ratz,PaulH
直到20世纪90年代，平滑肌的被动和主动长度-张力（L-T）关系被认为是静态的，对于每个肌肉长度具有单个被动力值和单个最大主动力值。然而，最近的研究表明，气道平滑肌中的活性L-T关系是动态的，并适应一段时间内长度的变化。此外，我们以前的工作表明，被动L-T关系在兔逼尿肌平滑肌（DSM）也是动态的，除了粘弹性行为，DSM显示应变软化行为的特点是在较短的长度后，一个新的较长的长度拉伸被动刚度的损失。这种被动刚度的损失似乎是不可逆的，当肌肉不产生主动力和次最大激活期间，但在完全肌肉激活时是可逆的，这表明应变软化损失的被动力的刚度分量在DSM中是可调节的。本研究表明，DSM的被动L-T曲线不是静态的，可以作为应变历史和激活历史的函数沿长度轴沿着移动。这项研究还表明，可调被动刚度（APS）可以调节给定肌肉长度的总力量（增加35%），而主动力量保持相对不变（增加4%）。这一发现表明，导致APS的结构与收缩装置平行作用，并且结果用于进一步证明我们之前提出的APS机械模型中建模元件的配置。
Until the 1990s, the passive and active length-tension (L-T) relationships of smooth muscle were believed to be static, with a single passive force value and a single maximum active force value for each muscle length. However, recent studies have demonstrated that the activeL-T relationship in airway smooth muscle is dynamic and adapts to length changes over a period of time. Furthermore, our prior work showed that the passiveL-T relationship in rabbit detrusor smooth muscle (DSM) is also dynamic and that in addition to viscoelastic behavior, DSM displays strain-softening behavior characterized by a loss of passive stiffness at shorter lengths following a stretch to a new longer length. This loss of passive stiffness appears to be irreversible when the muscle is not producing active force and during submaximal activation but is reversible on full muscle activation, which indicates that the stiffness component of passive force lost to strain softening is adjustable in DSM. The present study demonstrates that the passiveL-T curve for DSM is not static and can shift along the length axis as a function of strain history and activation history. This study also demonstrates that adjustable passive stiffness (APS) can modulate total force (35% increase) for a given muscle length, while active force remains relatively unchanged (4% increase). This finding suggests that the structures responsible for APS act in parallel with the contractile apparatus, and the results are used to further justify the configuration of modeling elements within our previously proposed mechanical model for APS.