Sugi H, Tanaka H, Wakabayashi K, Kobayashi T, Iwamoto H, Hamanaka T, Mitsui T, Amemiya Y
Biomed Biochim Acta. 1986;45(1-2):S15-22.
To obtain information about the structural changes in vertebrate skeletal muscle during contraction, time-resolved X-ray diffraction studies were performed on the intensity changes of the 59 A and 51 A actin layer lines from bullfrog sartorius muscle during the isometric force development, and the intensity changes of the 143 A and 215 A myosin meridional reflections and of the 1.0 and 1.1 equatorial reflections when isometrically contracting muscle was subjected to sinusoidal length changes (1%, 5-10 Hz) with the following results. The integrated intensities of the 59 A and 51 A actin layer lines increased during the force development by 30-50% for the 59 A reflection, and by about 70% for the 51 A reflection compared to their respective resting values. These intensity changes were greater than those taking place during the transition from rest to rigor state, and observed to precede the intensity changes of the 429 A myosin off-meridional reflection and of equatorial reflections. When sinusoidal length changes were applied to the muscle generating steady isometric force, the resulting periodic intensity changes in the 1.0 and 1.1 equatorial reflections were in phase and in antiphase with the length changes respectively. On the other hand, the 143 A myosin reflection exhibited a characteristic periodic changes; its intensity reached a maximum at each boundary between the stretch and release phases of the length changes. These results are discussed in connection with the behaviour of the cross-bridges during contraction.
为了获取脊椎动物骨骼肌收缩过程中的结构变化信息，我们进行了时间分辨X射线衍射研究，观察牛蛙缝匠肌在等长力发展过程中59 Å和51 Å肌动蛋白层线的强度变化，以及在等长收缩的肌肉受到正弦长度变化（1%，5 - 10 Hz）时143 Å和215 Å肌球蛋白子午线反射以及1.0和1.1赤道反射的强度变化，结果如下。与各自的静息值相比，在力发展过程中，59 Å肌动蛋白层线的积分强度增加了30 - 50%，51 Å肌动蛋白层线的积分强度增加了约70%。这些强度变化大于从静息状态到僵直状态转变过程中发生的变化，并且观察到其先于429 Å肌球蛋白离子午线反射和赤道反射的强度变化。当对产生稳定等长力的肌肉施加正弦长度变化时，1.0和1.1赤道反射中产生的周期性强度变化分别与长度变化同相和反相。另一方面，143 Å肌球蛋白反射表现出特征性的周期性变化；其强度在长度变化的拉伸和释放阶段之间的每个边界处达到最大值。结合收缩过程中横桥的行为对这些结果进行了讨论。
