体重对大鳍鳠力竭性运动后过量耗氧的影响

Effect of Body Weight on Excess Post-Exercise Oxygen Consumption in Mystus macropterus

过量耗氧（EPOC）是衡量动物无氧代谢能力的重要生理指标，为揭示不同体重鱼类在EPOC方面的适应机制，在25℃条件下对体重范围分别为低于20g、20～30g、30～50g和高于50g的大鳍鳠（Mystus macropterus Bleeker）力竭性运动后EPOC进行了测定。结果显示：实验鱼单位体重的静止耗氧率随体重的增加而显著下降（P〈0．05），分别为2．44、2．25、2．05和1．71mg·min^-1·kg^-1；力竭运动后实验鱼耗氧率迅速上升，然后缓慢回落到一稳定水平；其力竭性运动后耗氧率峰值出现时间随体重的上升而后延，分别为1．31、1．53、1．89和4．50min；其单位体重的耗氧率峰值随体重的增加而显著下降（P〈0．05），分别为12．36、11．07、10．27和7．20mg·min^-1·kg^-1，该数值分别为处理前的5．36、5．04、5．23和4．22倍；各体重组耗氧率下降到稳定水平的时间分别为20、20、25和20min，在此时间段高于静止耗氧率水平的耗氧量分别为69．25、64．89、62．15和49．07mg。研究表明大鳍鳠无氧代谢能力随体重的增加而上升。

The elevated oxygen consumption following exhaustive exercise, termed ＂excess post-exercise oxygen consumption＂ （EP- OC） can be used to assess the non-aerobic oxygen cost of exercise. To investigate the relationship between body weight and non-aerobic oxygen capacity, the effect of body weight （ below 20 g, 20 - 30 g, 30 - 50 g and above 50 g） on EPOC was studied in largefin longbarbel catfish （ Mystuz macropterus） at 25 ℃ by using a open-flow respirometer. The results show that resting oxygen consumption rates decrease significantly with the increase of body weight （p 〈0.05 ） and the values are 2.44, 2.25, 2.05 and 1.71 mgO2· min^-1 · kg^-1 for below 20 g, 20 - 30 g, 30 - 50 g and above 50 g body weight groups, respectively. Time to peak oxygen consumption rate increases with body size, which are 1.31, 1.53, 1.89 and 4.50 min for below 20 g, 20 - 30 g, 30 - 50 g and above 50 g body weight groups respectively. Peak oxygen consumption rates decrease significantly with the increase of body weight （p 〈0.05） and the values are 12.36, 11.07, 10.27 and 7.20 mg · min^-1 · kg^-1 for below 20 g, 20 -30 g, 30 -50 g and above 50 g body weight groups respectively, which are 5.36, 5.04, 5.23 and 4.22 that of resting oxygen consumption rate. The durations of post-exercise oxygen consumption to return to post-exercise stable level are 20, 20, 25 and 20 min respectively. The excess post-exercise oxygen consumption above resting oxygen consumption during this period are 69.25, 64.89, 62.15 and 49.07 mg respectively. This study show that the anaerobic metabolic capacity increased with the body weight in largefin longbarbel catfish.