High fliers: The physiology of bar-headed geese
High fliers: The physiology of bar-headed geese
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DOI：
10.1016/j.cbpa.2010.01.016
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发表时间：
2010-07-01
影响因子：
2.3
通讯作者：
Butler, Patrick J.
中科院分区：
文献类型：
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作者：
Butler, Patrick J.
世界上多达一半的斑头雁（Anser indicus）在中亚和印度之间迁徙，飞越喜马拉雅山脉时飞行在海拔5000米至9000米之间。在这些高度上的氧分压分别约为海平面的50%和30%。扑翼飞行是非常耗费能量的，那么斑头雁是如何在这样的高度迁徙的呢？斑头雁的血红蛋白比低地鸟类的血红蛋白对氧气有更大的亲和力，在严重缺氧的情况下，鸟类比哺乳动物更容易过度兴奋。总之，这意味着在一定的海拔高度，斑头雁的动脉血中的氧浓度要高于低地鸟类和哺乳动物。伴随换气过度的动脉血中CO2的低分压（低碳酸血症）不会像哺乳动物那样导致鸟类脑血流量减少，因此缺氧鸟类（包括斑头雁）比哺乳动物向大脑输送更多的氧气。圈养的斑头雁在模拟海拔8500 m的运动中不能维持较高的有氧代谢水平，其心脏每搏输出量远低于海平面运动。这表明，如果这种鹅的某些个体真的设法飞越珠峰峰，它们可能只有在获得垂直空气运动的帮助下才能做到，例如来自山脉顺风的背风波。(C)2010年爱思唯尔公司All rights reserved.
Up to half the world's population of bar-headed geese (Anser indicus) migrate between central Asia and India and fly between 5000 m and 9000 m above sea level as they cross the Himalayas. The partial pressures of oxygen at these altitudes are, respectively, about 50% and 30% those at sea level. Flapping flight is energetically expensive, so how are bar-headed geese able to migrate at such altitudes? The haemoglobin of bar-headed geese has a greater affinity for oxygen than those of lowland birds, and birds are able to hyperventilate to a greater extent than mammals during severe hypoxia. Together, these mean that the concentration of oxygen in the arterial blood at a given altitude is greater in bar-headed geese than in lowland birds and mammals. The low partial pressure of CO2 in arterial blood (hypocapnia) that accompanies hyperventilation does not cause reduction of cerebral blood flow in birds as it does in mammals, thus there is greater oxygen delivery to the brain in hypoxic birds, including bar-headed geese, than in mammals. Captive bar headed geese could not maintain elevated aerobic metabolism during exercise at a simulated altitude of 8500 m and their cardiac stroke volume was much lower than that during exercise at sea level. This suggests that if some individuals of this species of geese do really manage to fly over Mt Everest, they may only do so if they receive assistance from vertical air movements, for example from lee waves downwind from the mountains. (C) 2010 Elsevier Inc. All rights reserved.