CONTRACTILE PROPERTIES OF BUNDLES OF FIBER SEGMENTS FROM SKELETAL-MUSCLES
CONTRACTILE PROPERTIES OF BUNDLES OF FIBER SEGMENTS FROM SKELETAL-MUSCLES
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DOI：
10.1152/ajpcell.1982.243.1.c66
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发表时间：
1982-01-01
影响因子：
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通讯作者：
JONES, DA
中科院分区：
文献类型：
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作者：
FAULKNER, JA;CLAFLIN, DR;JONES, DA
本研究的目的是确定骨骼肌纤维节段束的收缩特性是否与完整纤维束的收缩特性显著不同。在青蛙肌肉中，纤维段和完整纤维的收缩性能之间的唯一差异是较低的最大缩短速度（VO）的纤维段。在哺乳动物[小鼠、大鼠、猫、狗]肌肉中，纤维节段束的收缩时间（TPT）、松弛时间（RT 1/2）和最大强直张力（Po）与完整纤维的收缩时间（TPT）、松弛时间（RT 1/2）和最大强直张力（Po）无差异，但张力发展速率（dP/dt）、抽搐与强直比率（Pt/PO）和VO较低。较低的dP/dt和Pt/PO是由于切割端附近的肌节受损导致顺应性增加。在离断端4-9 mm范围内，膜电位低于对照值，肌节在固定端收缩期间变长。在对未缩短的纤维节段的长度进行校正后，纤维节段的VO与完整纤维的VO没有差异。收缩特性的有效估计可以从骨骼肌纤维节段束获得。
The purpose of this study was to determine whether contractile properties of bundles of skeletal muscle fiber segments were significantly different from those of bundles of intact fibers. In frog muscles, the only difference between the contractile properties of fiber segments and intact fibers was a lower maximum velocity of shortening (VO) for the fiber segments. In mammalian [mouse, rat, cat, dog] muscles, the contraction time (TPT), relaxation time (RT1/2), and maximum tetanus tension (Po) of bundles of fiber segments were not different from those of intact fibers, but the rate of tension development (dP/dt), twitch-to-tetanus ratio (Pt/PO), and VO were lower. The lower dP/dt and Pt/PO resulted from increased compliance due to damaged sarcomeres near cut ends. Within 4-9 mm of a cut end, membrane potentials were less than control values, and sarcomeres lenghthened during a fixd-end contraction. After the length of fiber segments was corrected for the extact portion that was not shortening, the VO of fiber segments was not different from that of intact fibers. Valid estimates of contractile properties can be obtained from bundles of skeletal muscle fiber segments.