Control of sarcomere length in skinned muscle fibres of Rana temporaria during mechanical transients.
Control of sarcomere length in skinned muscle fibres of Rana temporaria during mechanical transients.
复制标题
机械瞬态过程中林蛙带皮肌纤维肌节长度的控制。
DOI：
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发表时间：
1984
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：
Y. Goldman;R. Simmons
描述了一种高速测量单面肌纤维条纹间距的新技术。振镜将氦氖激光以可变角度照射到肌肉纤维上。交叉条纹衍射的光由位置敏感光电探测器收集。使衍射光束集中到光电探测器上所需的入射角与肌节长度有关。通过与复合显微镜测量结果的比较，对该仪器进行了测试。在这两种方法之间观察到每半个肌节几纳米的差异。当激光束的入射角随其平均位置呈正弦变化时，差异的大小减小。在肌肉纤维的稳定被动缩短过程中，衍射仪的输出经常显示出停顿和短暂的快速缩短。通过振荡激光束的入射角，在一系列照明角度上平均肌节长度输出，消除了这些不规则性。结果表明，在每半个肌节几纳米的空间分辨率下，体积衍射效应会导致从相干光衍射角度测量的肌节表观长度与平均条纹间距不同。在入射角振荡下，设备的时间和空间分辨率都令人满意，可以将肌节长度信号反馈给用于“肌节长度钳”的长度控制器。在主动收缩中，刚性与亚饱和钙浓度下稳定发展的张力密切相关。在一定的拉伸水平下，剥皮后的纤维比完整纤维的硬度要低。
A new technique is described for high‐speed measurement of striation spacing of single skinned muscle fibres. A galvanometer mirror directs helium‐neon laser light on to the muscle fibre at a variable angle. Light diffracted by the cross‐striations is collected by a position‐sensitive photodetector. The incident angle necessary to centre the diffracted light beam on to the photodetector is related to sarcomere length. The instrument was tested by comparison with measurements obtained with a compound microscope. Discrepancies of several nanometers per half sarcomere were observed between these two methods. When the incident angle of the laser beam was varied sinusoidally about its mean position the magnitude of the discrepancy was reduced. During steady passive shortening of the muscle fibres the output of the diffraction instrument often displayed pauses and brief periods of rapid shortening. These irregularities were eliminated by averaging the sarcomere length output over a range of illumination angles by oscillating the incident angle of the laser beam. The results suggest that at the spatial resolution of several nanometers per half sarcomere, volume diffraction effects can cause the apparent sarcomere length measured from the angle of coherent light diffraction to differ from the mean striation spacing. With incident‐angle oscillation the time and spatial resolution of the equipment were satisfactory for the sarcomere length signal to be fed back to a length controller for a 'sarcomere length clamp'. In active contractions, stiffness was closely related to steady developed tension at sub‐saturating calcium concentrations. Skinned fibres are less stiff than intact fibres at a given level of developed tension.