Sugi H, Kobayashi T
Adv Exp Med Biol. 1984;170:623-35. doi: 10.1007/978-1-4684-4703-3_58.
By use of an optical system, with which the beam of the first-order diffraction line of He-Ne laser light from a single frog skeletal muscle fiber was split by the wedge-shaped mirror to be focused on two photodiodes ( Haugen & Sten - Knudsen , 1976), small changes in sarcomere length (less than 1 A) could be recorded during quick fiber length changes (up to 1.2% of Lo, complete within 0.2-0.4 msec) applied at the plateau of isometric tetanus. Data were only obtained on fibers which showed typical sinusoidal sarcomere length changes in response to sinusoidal fiber length changes during tetanus with a linear relation between their magnitudes. Measurements of sarcomere length changes were made at various points along the fiber length. The interval between the onset of fiber length changes at one fiber end and that of force change recorded at the fixed fiber end was explained by the propagation of mechanical impulse at about 180 m/sec. In the case of quick releases, the onset of sarcomere shortening near the fixed fiber end tended to take place after that of force change, especially with long fibers, indicating that the drop in force during a quick release may not always be associated with sarcomere shortening along the entire fiber length. This implies that the force changes in response to rapid length changes may not give correct information about the cross-bridge properties. Irrespective of the point at which sarcomere shortening was recorded, it was always observed that the onset of quick force recovery occurred while sarcomere shortening was still in progress. Such a phenomenon can be simulated by a viscoelastic multi-segment model with series elasticity located in each segment.
通过使用一种光学系统，来自单个青蛙骨骼肌纤维的氦氖激光一级衍射线束被楔形镜分开，聚焦在两个光电二极管上（豪根和斯滕 - 克努森，1976年），在等长强直收缩平台期施加快速纤维长度变化（高达Lo的1.2%，在0.2 - 0.4毫秒内完成）时，肌节长度的微小变化（小于1埃）能够被记录下来。仅在那些在强直收缩期间对正弦形纤维长度变化呈现典型正弦形肌节长度变化且二者大小呈线性关系的纤维上获取了数据。沿着纤维长度的不同点进行了肌节长度变化的测量。纤维一端纤维长度变化的起始与固定纤维端记录到的力变化的起始之间的时间间隔，可通过机械冲动以约180米/秒的速度传播来解释。在快速释放的情况下，固定纤维端附近肌节缩短的起始往往在力变化之后发生，尤其是对于长纤维，这表明快速释放期间的力下降可能并不总是与整个纤维长度上的肌节缩短相关联。这意味着响应快速长度变化的力变化可能无法给出关于横桥特性的正确信息。无论在哪个点记录肌节缩短，总是观察到快速力恢复的起始发生在肌节缩短仍在进行时。这种现象可以用一个在每个节段都有串联弹性的粘弹性多节段模型来模拟。
