Fast-start muscle dynamics in the rainbow trout Oncorhynchus mykiss:: phase relationship of white muscle shortening and body curvature
Fast-start muscle dynamics in the rainbow trout Oncorhynchus mykiss:: phase relationship of white muscle shortening and body curvature
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DOI：
10.1242/jeb.01433
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发表时间：
2005-03-01
影响因子：
2.8
通讯作者：
Gosline, JM
中科院分区：
文献类型：
--
作者：
Goldbogen, JA;Shadwick, RE;Gosline, JM
用超声显微测量法研究了虹鳟（Oncorhynchus mykiss）在诱导快速启动过程中肌节外侧快纤维长度的变化。同时高速摄像允许中线运动学分析，以估计在身体变形过程中发生的肌肉紧张程度。这些数据的比较被用来检查非定常，大幅度机动过程中局部肌肉缩短和局部身体弯曲之间的相位关系。我们的分析发现，肌肉缩短是暂时解耦的身体弯曲，可能是由于水动力的影响。相移是这样的中线曲率落后于肌肉缩短在前（0.4L，其中L是叉长度）和后（0.7L）轴向位置。较强的逃逸反应与高峰应变和快速应变波速度，但不快曲率波速度。在这些高应变条件下，后位置的相移显著增加，而前位置不受影响。在低应变条件下，在两个轴向位置仍然观察到曲率滞后，这表明在较弱的逃逸响应期间，水动力仍然很重要。这些数据支持了先前的模型，该模型表明快速启动身体弯曲是由肌肉扭矩和沿身体沿着的流体动力学阻力之间的相互作用决定的。
Muscle length changes of the lateral myotomal fast fibers of rainbow trout (Oncorhynchus mykiss) were measured using sonomicrometry during induced fast-starts. Simultaneous high-speed videography allowed for the analysis of midline kinematics to estimate the degree of muscle strain that occurs during body deformation. Comparison of these data was used to examine the phase relationship between local muscle shortening and local body bending during unsteady, large amplitude maneuvers. Our analysis finds that muscle shortening is temporally decoupled from body bending, probably due to the influence of hydrodynamic forces. The phase shift was such that midline curvature lagged behind muscle shortening at both the anterior (0.4L, where L is fork length) and posterior (0.7L) axial positions. Stronger escape responses were correlated with high peak strains and rapid strain-wave velocities, but not faster curvature-wave velocities. Under these conditions of high strain, the phase shift at the posterior position is significantly increased, whereas the anterior position fails to be affected. Curvature lag was still observed at both axial locations under conditions of low strain, suggesting that hydrodynamic forces are still significant during weaker escape responses. These data support a previous model that suggests fast-start body bending is determined by the interaction between muscle torque and hydrodynamic resistance along the body.