Coughlin David J, Carroll Andrew M
Department of Biology, Widener University Chester, PA 19013, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2006 Dec;145(4):533-9. doi: 10.1016/j.cbpa.2006.08.026. Epub 2006 Aug 30.
Recent work has employed video and sonometric analysis combined with hydrodynamic modeling to estimate power output by the feeding musculature of largemouth bass in feeding trials. The result was an estimate of approximately 69 W kg(-1) of power by the epaxial muscle during maximal feeding strikes. The present study employed in vitro measurements of force, work and power output by fast-twitch epaxial muscle bundles stimulated under activation conditions measured in vivo to evaluate the power output results of the feeding experiments. Isolated muscle bundles from the epaxial muscle, the sternohyoideus and the lateral red or slow-twitch muscle were tied into a muscle mechanics apparatus, and contractile properties during tetanic contractions and maximum shortening velocity (Vmax) were determined. For the epaxial muscles, work and power output during feeding events was determined by employing mean stimulation conditions derived from a select set of maximal feeding trials: 17% muscle shortening at 3.6 muscle lengths/s, with activation occurring 5 ms before the onset of shortening. Epaxial and sternohyoideus muscle displayed similar contractile properties, and both were considerably faster (Vmax approximately 11-13 ML s(-1)) than red muscle (Vmax approximately 5 ML s(-1)). Epaxial muscle stimulated under in vivo activation conditions generated approximately 60 W kg(-1) with a 17% strain and approximately 86 W kg(-1) with a 12% strain. These values are close to those estimated by hydrodynamic modeling. The short lag time (5 ms) between muscle activation and muscle shortening is apparently a limiting parameter during feeding strikes, with maximum power found at an offset of 15-20 ms. Further, feeding strikes employing a faster shortening velocity generated significantly higher power output. Power production during feeding strikes appears to be limited by the need for fast onset of movement and the hydrodynamic resistance to buccal expansion.
最近的研究工作采用了视频和声测分析，并结合流体动力学模型，在摄食试验中估算大口黑鲈摄食肌肉组织的功率输出。结果显示，在最大摄食攻击过程中，轴上肌的功率输出约为69 W kg⁻¹。本研究采用体外测量方法，对在体内测量的激活条件下刺激的快肌轴上肌束的力、功和功率输出进行评估，以验证摄食实验的功率输出结果。从轴上肌、胸骨舌骨肌和外侧红色或慢肌中分离出的肌束被系在肌肉力学装置上，并测定强直收缩和最大缩短速度（Vmax）期间的收缩特性。对于轴上肌，摄食过程中的功和功率输出是通过采用一组选定的最大摄食试验得出的平均刺激条件来确定的：肌肉缩短17%，速度为3.6个肌长/秒，激活在缩短开始前5毫秒发生。轴上肌和胸骨舌骨肌表现出相似的收缩特性，两者都比红色肌肉（Vmax约为5个肌长/秒）快得多（Vmax约为11 - 13个肌长/秒）。在体内激活条件下刺激的轴上肌在17%应变时产生约60 W kg⁻¹的功率，在12%应变时产生约86 W kg⁻¹的功率。这些值与流体动力学模型估计的值接近。肌肉激活和肌肉缩短之间的短延迟时间（5毫秒）显然是摄食攻击期间的一个限制参数，最大功率出现在15 - 20毫秒的偏移处。此外，采用更快缩短速度的摄食攻击产生的功率输出显著更高。摄食攻击期间的功率产生似乎受到快速开始运动的需求和口腔扩张的流体动力学阻力的限制。
