Kawai M, Brandt P, Orentlicher M
Biophys J. 1977 May;18(2):161-72. doi: 10.1016/S0006-3495(77)85605-1.
In intact single crayfish muscle fibers and frog semitendinosus muscles we have studied the tension response to sinusoidal length changes in the frequency range of 0.25-133 Hz. By this method we have resolved three processes in the interaction of myosin cross-bridges with actin in fully activated preparations. They are (A) a low-frequency phase advance, (B) a middle-frequency delay, and (C) a high-frequency advance. These processes can be used as probes to study the chemomechanical coupling of contractility. Process (B) represents net power output from the muscle preparation (oscillatory work). With maximal K or caffeine activation of crayfish muscle at 20 degrees C, it decreases to zero in the initial 45 s of maintained tension. Similar results were obtained with frog semitendinosus whole muscles. We interpret this decrease of (B) with time as a gradual decrease in actomyosin ATP-hydrolysis rate.
在完整的单个小龙虾肌肉纤维和青蛙半腱肌中，我们研究了在0.25 - 133Hz频率范围内对正弦长度变化的张力反应。通过这种方法，我们在完全激活的制剂中解析了肌球蛋白横桥与肌动蛋白相互作用的三个过程。它们是：(A)低频相位超前，(B)中频延迟，以及(C)高频超前。这些过程可用作研究收缩性化学机械偶联的探针。过程(B)代表肌肉制剂的净功率输出（振荡功）。在20℃下用最大浓度的K或咖啡因激活小龙虾肌肉时，在保持张力的最初45秒内它降至零。青蛙半腱肌整体肌肉也得到了类似结果。我们将(B)随时间的这种下降解释为肌动球蛋白ATP水解速率的逐渐降低。
