Relationship between short-range stiffness and yielding in type-identified, chemically skinned muscle fibers from the cat triceps surae muscles.
Relationship between short-range stiffness and yielding in type-identified, chemically skinned muscle fibers from the cat triceps surae muscles.
复制标题
猫小腿三头肌的类型鉴定化学剥皮肌纤维的短程刚度与屈服之间的关系。
DOI：
10.1152/jn.1996.76.4.2280
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Nichols,TR
中科院分区：
文献类型：
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作者：
Malamud,JG;Godt,RE;Nichols,TR
1.研究了猫后肢化学剥皮肌纤维的瞬态牵张力反应。这些实验的目的是确定短程刚度，即在第一个0.5%的长度变化上由纤维施加的表观刚度，在I型肌纤维中比II型肌纤维高的程度。纤维从比目鱼肌和股中间肌获得，其主要含有I型纤维，LGm，外侧腓肠肌的一个隔间，其主要含有II型纤维，和LG 3，混合型隔间。2.在0.5肌肉长度/s（ML/s）拉伸过程中，超过约1%肌肉长度的短范围，大多数纤维表现出明显的刚度或屈服的突然下降。来自主要含有S型（慢颤，或I型）纤维的肌肉、比目鱼肌和股中间肌的纤维表现出明显的刚度下降，使得在持续拉伸期间力也下降。来自LG 3隔室的大多数纤维可以分为两个不同的组，这取决于它们在0.5ML/s的拉伸速度下是否显示出力屈服。3.在第一个0.5%的拉伸测量的短程刚度是更大的纤维显示力屈服比那些没有在匹配的初始力和归一化的拉伸振幅。这一结果与赋予纤维高短程刚度的相同机制也导致更大程度的屈服的假设一致。4.来自比目鱼肌的纤维被发现表现出超过200倍速度范围（0.01-2 ML/s）的力屈服。与此相反，大多数纤维从LGm室只显示出增加的程度与拉伸速度的屈服。这些纤维中的一些最终屈服于力，但只有当它们以> 2 ML/s的速度拉伸时。所提出的高短程刚度和屈服之间的关系得到以下发现的支持：短程刚度在纤维屈服程度增加最大的速度范围内急剧增加。5.生理实验后，纤维进行SDS凝胶电泳。在低分子量范围内的两种不同的模式的频带被发现对应于两种类型的基础上，其动态力学性能被确定。在0.5 ML/s下不屈服的纤维显示出与兔腰大肌（II型）纤维非常相似的带状图案。6.这些结果支持的假设，I型纤维是专门在提出一个高的短程刚度的反射机制之前，有效的姿势控制，这种属性的结果从纤维的内在特性，而不是由于I型和II型纤维的尺寸差异。屈服用于保护纤维在伸长收缩期间免受破坏力水平的影响。这些瞬态性能的重要性，肌肉的机械行为在正在进行的运动中建议的观察，高刚度，其次是屈服是重复的，在连续的拉伸过程中几乎没有变化。
1. Transient, stretch-evoked force responses of chemically skinned muscle fibers from the cat hindlimb were investigated. The purpose of these experiments was to determine the exent to which short-range stiffness, the apparent stiffness exerted by the fiber over the first 0.5% of length change, is higher in type I than type II muscle fibers. Fibers were obtained from soleus and vastus intermedius muscles, which contain predominantly type I fibers, the LGm, a compartment of the lateral gastrocnemius muscle that contains predominantly type II fibers, and LG3, a compartment of mixed type. 2. Beyond a short range of approximately 1% of muscle length during a 0.5 muscle length/s (ML/s) stretch, most fibers exhibited an abrupt decrease in apparent stiffness or yield. Fibers from the muscles containing predominantly type S (slow twitch, or type I) fibers, soleus and vastus intermedius, exhibited such a pronounced decline in apparent stiffness that force declined as well during continued stretch. Most of the fibers from the LG3 compartment could be divided into two distinct groups depending upon whether or not they showed a force yield at the stretch velocity of 0.5 ML/s. 3. The short-range stiffness measured over the first 0.5% of stretch was greater for fibers showing force yield than for those that did not at matched initial forces and normalized stretch amplitudes. This result is consistent with the hypothesis that the same mechanism that endows the fiber with high short-range stiffness is also responsible for a greater extent of yielding. 4. Fibers from soleus were found to exhibit a force yield over a 200-fold range of velocities (0.01-2 ML/s). In contrast, most fibers from the LGm compartment showed only an increase in extent of yield with stretch velocity. Some of these fibers eventually yielded in force, but only when they were stretched at velocities > 2 ML/s. The proposed relationship between high short-range stiffness and yielding was supported by the finding that short-range stiffness increased sharply in the range of velocities where the fiber showed the greatest increase in extent of yield. 5. After the physiological experiments, fibers were subjected to SDS gel electrophoresis. Two distinct patterns of bands in the low molecular weight range were found to correspond to the two types that were identified on the basis of their dynamic mechanical properties. Fibers that did not yield at 0.5 ML/s showed a band pattern very similar to that of rabbit psoas (type II) fibers. 6. These results support the hypothesis that type I fibers are specialized in presenting a high short-range stiffness for effective postural control in advance of reflex mechanisms and that this property results from intrinsic properties of the fiber and is not due to differences in the dimensions of type I and II fibers. Yielding serves to protect the fiber from damaging levels of force during lengthening contractions. The importance of these transient properties to the mechanical behavior of muscle during ongoing movements is suggested by the observation that high stiffness followed by yielding is repeated with little alteration during successive stretches.