Clutterham S, Gamperl A K, Wallace H L, Crawshaw L I, Farrell A P
Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.
Physiol Biochem Zool. 2004 Jul-Aug;77(4):611-8. doi: 10.1086/422053.
We tested the hypothesis that juvenile rainbow trout (Oncorhynchus mykiss) would select a temperature colder than their acclimation temperature (16 deg +/-1 deg C) to minimize postexhaustive exercise metabolic demands and enhance oxygen availability. After an initial 3-h exploratory period in a thermal gradient (6 degrees -25 degrees C), fish selected a temperature of approximately 14 degrees C and had a baseline exploratory swimming activity of approximately 60 cm min(-1). Subsequently, experimental (chased) fish were individually removed, exhaustively exercised for 1.5 min, and replaced. Both control (unchased) and experimental fish were allowed to explore the thermal gradient for another 2 h. Immediately after being chased, trout had a metabolic profile that was consistent with being exhausted; levels of plasma and muscle lactate were 4.38+/-0.25 mmol L(-1) and 28.0+/-2.0 mmol kg(-1), respectively, and levels of muscle glycogen, adenosine triphosphate, and phosphocreatine were 3.89+/-0.95, 4.23+/-0.62, and 3.07+/-0.73 mmol kg(-1), respectively. Although exploratory swimming activity of the chased fish was significantly lower (by 81%) as compared with control fish during the first 5 min postchase, differences in the mean, median, and mode values for selected temperatures during the next 2 h were neither large (<1 degrees C) nor significant (P>0.05). Contrary to our initial hypothesis, these findings suggest that juvenile rainbow trout do not select a colder temperature to decrease metabolic rate following exhaustive exercise. Instead, rainbow trout selected a temperature marginally cooler than their acclimation temperature (16 degrees C) regardless of whether they had been previously exhausted.
幼年虹鳟（Oncorhynchus mykiss）会选择一个比其驯化温度（16℃±1℃）更低的温度，以将力竭运动后的代谢需求降至最低，并提高氧气供应。在热梯度（6℃-25℃）中经过初始3小时的探索期后，鱼选择了约14℃的温度，并且基线探索性游泳活动约为60厘米/分钟。随后，将实验（追逐）鱼单独捞出，进行1.5分钟的力竭运动，然后放回。对照（未追逐）鱼和实验鱼都被允许在热梯度中再探索2小时。刚被追逐后，虹鳟的代谢特征与力竭状态一致；血浆和肌肉乳酸水平分别为4.38±0.25毫摩尔/升和28.0±2.0毫摩尔/千克，肌肉糖原、三磷酸腺苷和磷酸肌酸水平分别为3.89±0.95、4.23±0.62和3.07±0.73毫摩尔/千克。尽管在追逐后的前5分钟内，被追逐鱼的探索性游泳活动与对照鱼相比显著降低（降低了81%），但在接下来2小时内所选温度的平均值、中位数和众数的差异既不大（<1℃）也不显著（P>0.05）。与我们最初的假设相反，这些发现表明，幼年虹鳟在力竭运动后不会选择更低的温度来降低代谢率。相反，虹鳟选择了一个比其驯化温度（16℃）略低的温度，无论它们之前是否已经力竭。
