Coughlin David J, Spiecker Amy, Schiavi Jonathan M
Department of Biology, Widener University, One University Place, Chester, PA 19013, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2004 Jan;137(1):151-60. doi: 10.1016/s1095-6433(03)00285-x.
Rainbow trout (Oncorhynchus mykiss) and brook trout (or charr, Salvelinus fontinalis) display different rostral-caudal patterns of power production by the red or aerobic muscle during steady swimming. The anterior muscle of rainbow trout produces much less power for swimming than the posterior, while in brook trout there is no variation in power output. To determine if red muscle recruitment is associated with anterior-posterior patterns of power production, electromyography (EMG) was used to record red muscle activity at three body positions across a range of swimming speeds in fish of each species. The initial recruitment of the anterior red muscle in swimming rainbow trout was predicted to lag behind, i.e. occur at higher speeds, that of the posterior due to the variation in power production, but no variation in recruitment was expected for brook trout. Burst of red muscle EMG activity occurring with each tailbeat was analyzed for frequency (tailbeat frequency), duty cycle (DC) (duration of burst relative to the period of the tailbeat) and burst intensity (BI) (magnitude of the measured EMG activity). Brook trout swam with higher tailbeat frequencies and longer values of DC than rainbow trout. Both species showed a pattern of longitudinal variation in DC, with longer DC values in the anterior red muscle. BI also differed significantly along the length of rainbow trout but not brook trout. In the former, BI of anterior muscle was significantly less than the posterior at lower steady swimming speeds. The EMG data suggest that power production and muscle recruitment are related. In rainbow trout, where there is longitudinal variation in muscle power output, there are also significant rostral-caudal differences in red muscle recruitment.
虹鳟（Oncorhynchus mykiss）和溪鳟（或红点鲑，Salvelinus fontinalis）在稳定游泳过程中，红色或有氧肌肉产生功率的吻端至尾端模式不同。虹鳟的前部肌肉在游泳时产生的功率比后部少得多，而溪鳟的功率输出没有变化。为了确定红色肌肉的募集是否与功率产生的前后模式相关，使用肌电图（EMG）记录了每个物种的鱼在一系列游泳速度下三个身体位置的红色肌肉活动。由于功率产生的差异，预计游泳的虹鳟前部红色肌肉的初始募集会落后于后部，即在更高的速度下发生，但预计溪鳟的募集没有变化。分析了每次尾鳍摆动时出现的红色肌肉EMG活动爆发的频率（尾鳍摆动频率）、占空比（DC）（爆发持续时间相对于尾鳍摆动周期）和爆发强度（BI）（测量的EMG活动幅度）。溪鳟游泳时的尾鳍摆动频率比虹鳟高，DC值也更长。两个物种都显示出DC的纵向变化模式，前部红色肌肉的DC值更长。虹鳟的BI沿身体长度也有显著差异，但溪鳟没有。在前者中，在较低的稳定游泳速度下，前部肌肉的BI明显小于后部。EMG数据表明功率产生与肌肉募集有关。在虹鳟中，肌肉功率输出存在纵向变化，红色肌肉募集在吻端至尾端也存在显著差异。
