Hindle A G, Senkiw R W, Macarthur R A
Department of Zoology, University of Manitoba, Winnipeg, MB, Canada R3T 2N2.
Comp Biochem Physiol A Mol Integr Physiol. 2006 Jun;144(2):232-41. doi: 10.1016/j.cbpa.2006.03.001. Epub 2006 Apr 19.
We tested the hypothesis that immersion hypothermia enhances the diving capabilities of adult and juvenile muskrats by reducing rates of oxygen consumption (V O2). Declines in abdominal body temperature (T(b)) comparable to those observed in nature (0.5-3.5 degrees C) were induced by pre-chilling animals in 6 degrees C water. Pre-chilling did not reduce diving V O2 of any animal tested in 10 degrees C or 30 degrees C water, irrespective of the nature of the dive. Most behavioural indices of dive performance, including average and cumulative dive times, were unaffected by T(b) reduction in adults, but depressed in hypothermic juveniles (200-400 g). Hypothermia reduced diving heart rate only on short (<25s) dives (16% reduction, P=0.01), but did not affect the temporal onset of diving bradycardia. Post-immersion V O2 was higher for pre-chilled than for normothermic muskrats, but the difference became insignificant on longer (>90 s) dives. Our findings suggest that the mild hypothermia experienced by muskrats in nature has minimal effect on diving and post-immersion metabolic costs, and thus has little impact on the dive performance of this northern semi-aquatic mammal.
浸入式低温通过降低耗氧率（V O2）来增强成年和幼年麝鼠的潜水能力。通过将动物预先置于6摄氏度的水中冷却，使其腹部体温（T(b)）下降，下降幅度与在自然环境中观察到的相当（0.5 - 3.5摄氏度）。无论潜水性质如何，预先冷却并未降低在10摄氏度或30摄氏度水中测试的任何动物的潜水V O2。大多数潜水表现的行为指标，包括平均和累计潜水时间，在成年动物中不受T(b)降低的影响，但在低温的幼年麝鼠（200 - 400克）中则有所下降。低温仅在短时间（<25秒）潜水时降低潜水心率（降低16%，P = 0.01），但不影响潜水心动过缓的时间起始。预先冷却的麝鼠浸入后V O2高于体温正常的麝鼠，但在较长时间（>90秒）潜水时，这种差异变得不显著。我们的研究结果表明，麝鼠在自然环境中经历的轻度低温对潜水和浸入后代谢成本的影响最小，因此对这种北方半水生哺乳动物的潜水表现影响很小。
