The relation between stiffness and filament overlap in stimulated frog muscle fibres.
The relation between stiffness and filament overlap in stimulated frog muscle fibres.
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受刺激的青蛙肌肉纤维的硬度和丝重叠之间的关系。
DOI：
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发表时间：
1981
期刊：
影响因子：
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通讯作者：
R. Simmons
中科院分区：
文献类型：
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作者：
L. E. Ford;A. Huxley;R. Simmons
1. 在0 ~ 1℃的强电刺激下，记录了蛙胫骨前肌分离纤维在肌节长度为2.0 ~ 3.2 mm处的张力瞬态。选定部分纤维的长度由一个点跟随装置的反馈控制。该步骤在0.2 ms内完成，力传感器的固有频率为10.8 kHz。3. 通过将张力记录与模拟电路（延迟线）的输出进行比较来分析瞬态，模拟电路（延迟线）包含代表(a)力传感器响应，(b)纤维惯性，(c)周围流体的粘度和惯性，(d)纤维的被动刚度和粘度，(e)肌腱顺应性和(f)收缩装置的刚度和早期张力恢复的组件。4. 在不同肌节长度的释放中，瞬时刚度和早期张力恢复归因于收缩装置几乎完全与发展的张力成比例。在过渡的后期阶段，有轻微的偏离比例。5. 结果证实了整个瞬变过程代表了交叉桥中的事件。6. 在完全重叠的情况下，可归因于交叉桥的顺应性至少占光纤瞬时顺应性测量值的80%，甚至可能远远超过90%。因此，刚度可以用来衡量连接的十字桥的数量。7. 结果表明，如果灯丝和Z线顺应性可以忽略不计，则使十字桥中的张力从等距值降至零所需的粗丝相对于细丝的瞬时滑动移动量约为3.9 nm。然而，不排除灯丝顺应性虽然很小，但可能足以将该数字降低到3.5 nm或3.1 nm。快速拉伸响应与释放响应不同，不能很好地与延迟线匹配。这些偏差表明，瞬时弹性在拉伸时是非线性的。9. 在所有肌节长度的静止纤维中，张力响应的第一个峰值主要由纤维惯性和粘度决定，而不是由弹性决定。
1. Tension transients were recorded at sarcomere lengths from 2.0 to 3.2 mum in isolated fibres from the tibialis anterior muscle of frogs during tetanic stimulation at 0‐1 degrees C. 2. The length of a selected portion of the fibre was controlled by feed‐back from a spot‐follower device. The step was complete in 0.2 ms and the natural frequency of the force transducer was 10.8 kHz. 3. The transients were analysed by comparing the tension record with the output of an analogue circuit (delay line) which contained components representing (a) force transducer response, (b) fibre inertia, (c) viscosity and inertia of surrounding fluid, (d) passive stiffness and viscosity of the fibre, (e) tendon compliance and (f) stiffness and early tension recovery of the contractile apparatus. 4. In releases at different sarcomere lengths, the instantaneous stiffness and the early tension recovery attributed to the contractile apparatus varied almost exactly in proportion to the developed tension. In the later phases of the transient there were minor deviations from proportionality. 5. The results confirm that the entire transient represents events in the cross‐bridges. 6. At full overlap, the compliance attributable to the cross‐bridges is at least 80%, and probably well over 90% of the measured instantaneous compliance of the fibre. Stiffness can therefore be used as a measure of the number of attached cross‐bridges. 7. The amount of instantaneous sliding movement of thick relative to thin filaments required to bring tension in a cross‐bridge from the isometric value to zero is about 3.9 nm if filament and Z‐line compliance are negligible, as suggested by the results. It is not however excluded that filament compliance, though small, may be sufficient to reduce this figure to 3.5 nm or possibly 3.1 nm. 8. The responses to quick stretch, unlike those to release, could not be satisfactorily matched with the delay line. The deviations suggest that the instantaneous elasticity is non‐linear in stretches. 9. In resting fibres at all sarcomere lengths, the first peak of the tension response was determined chiefly by fibre inertia and viscosity, rather than elasticity.