Yuri K, Wakayama J, Yamada T
Department of Physics, Faculty of Science, Science University of Tokyo, Shinjuku-ku, Tokyo, 162-8601, Japan.
J Biochem. 1998 Sep;124(3):565-71. doi: 10.1093/oxfordjournals.jbchem.a022149.
The isometric contractile properties of single myofibrils of rabbit skeletal muscle were studied at various sarcomere lengths. Single myofibrils were suspended between the tips of one rigid and one flexible glass microneedle, and their force production was determined by detecting the bending of the flexible microneedle photo-electronically. The active force vs. sarcomere length relation had an ascending limb (0.7-2.25 micron), a plateau (2.25-2.5 micron), and a descending limb (2.5-3.8 micron), which was similar to that of frog skeletal muscle. The passive force became increasingly apparent beyond a sarcomere length of 2.4 micron. These results can reasonably be explained based on the sliding filament mechanism by assuming the sarcomere geometry of rabbit muscle. The plateau, with a produced force of about 256 kN/m2, and the linear decline of force in the descending limb of the single myofibrils were essentially the same as those for frog muscle fibers. However, the slope of the force decline in the ascending limb was far steeper than that for frog muscle. This suggests that internal elements of sarcomeres are different between rabbit and frog muscles.
在不同的肌节长度下研究了兔骨骼肌单个肌原纤维的等长收缩特性。单个肌原纤维悬挂在一根刚性玻璃微针和一根柔性玻璃微针的尖端之间，通过光电检测柔性微针的弯曲来确定其产生的力。主动力与肌节长度的关系有一个上升支（0.7 - 2.25微米）、一个平台期（2.25 - 2.5微米）和一个下降支（2.5 - 3.8微米），这与青蛙骨骼肌的情况相似。在肌节长度超过2.4微米时，被动力变得越来越明显。基于滑动丝机制，通过假设兔肌肉的肌节几何结构，可以合理地解释这些结果。单个肌原纤维的平台期产生的力约为256 kN/m²，下降支中力的线性下降与青蛙肌肉纤维的情况基本相同。然而，上升支中力下降的斜率比青蛙肌肉的要陡得多。这表明兔和青蛙肌肉的肌节内部成分不同。
