Kieffer J D, Wakefield A M, Litvak M K
Department of Biology and Centre for Coastal Studies and Aquaculture, University of New Brunswick, PO Box 5050, Saint John, New Brunswick, Canada E2L 4L5.
J Exp Biol. 2001 Dec;204(Pt 24):4281-9. doi: 10.1242/jeb.204.24.4281.
Experiments were conducted to determine the physiological responses to exercise of Atlantic sturgeon (Acipenser oxyrhynchus) and shortnose sturgeon (A. brevirostrum). We measured the rates of oxygen consumption and ammonia excretion in both species and a variety of physiological parameters in both muscle (e.g. lactate, glycogen, pyruvate, glucose and phosphocreatine concentrations) and blood (e.g. osmolality and lactate concentration) in juvenile shortnose sturgeon following 5 min of exhaustive exercise. In both species, oxygen consumption and ammonia excretion rates increased approximately twofold following exhaustive exercise. Post-exercise oxygen consumption rates decreased to control levels within 30 min in both sturgeon species, but post-exercise ammonia excretion rates remained high in Atlantic sturgeon throughout the 4 h experiment. Resting muscle energy metabolite levels in shortnose sturgeon were similar to those of other fish species, but the levels decreased only slightly following the exercise period and recovery occurred within an hour. Under resting conditions, muscle lactate levels were low (<1 micromol g(-1)) but they increased to approximately 6 micromol g(-1) after exercise, returning to control levels within 6 h. Unlike similarly stressed teleost fish, such as the rainbow trout, plasma lactate levels did not increase substantially and returned to resting levels within 2 h. Plasma osmolality was not significantly affected by exercise in shortnose sturgeon. Taken together, these results suggest that shortnose and Atlantic sturgeon do not exhibit the physiological responses to exhaustive exercise typical of other fish species. They may possess behavioural or endocrinological mechanisms that differ from those of other fishes and that lead to a reduced ability to respond physiologically to exhaustive exercise.
开展了实验以确定大西洋鲟（Acipenser oxyrhynchus）和短吻鲟（A. brevirostrum）对运动的生理反应。我们测量了这两个物种的耗氧率和排氨率，以及在短吻鲟幼鱼进行5分钟力竭运动后，其肌肉（如乳酸、糖原、丙酮酸、葡萄糖和磷酸肌酸浓度）和血液（如渗透压和乳酸浓度）中的各种生理参数。在这两个物种中，力竭运动后耗氧率和排氨率均增加了约两倍。两种鲟鱼在运动后30分钟内耗氧率均降至对照水平，但在整个4小时的实验中，大西洋鲟运动后的排氨率一直很高。短吻鲟静止肌肉中的能量代谢物水平与其他鱼类相似，但运动后这些水平仅略有下降，且在一小时内恢复。在静止条件下，肌肉乳酸水平较低（<1微摩尔/克），但运动后增加到约6微摩尔/克，在6小时内恢复到对照水平。与同样受到应激的硬骨鱼如虹鳟不同，短吻鲟血浆乳酸水平没有大幅增加，而是在2小时内恢复到静止水平。短吻鲟的血浆渗透压不受运动的显著影响。综合来看，这些结果表明，短吻鲟和大西洋鲟对力竭运动的生理反应并不表现出其他鱼类典型的特征。它们可能具有与其他鱼类不同的行为或内分泌机制，导致其在生理上对力竭运动的反应能力降低。
