Department of Biology, University of Utah, 257 S. 1400 E., Salt Lake City, UT 84112, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2010 Feb;155(2):146-53. doi: 10.1016/j.cbpa.2009.10.023. Epub 2009 Oct 24.
The highly derived mechanism birds use to ventilate their lungs relies on dorsoventral excursions of their heavily muscled sternum and abdominal viscera. Our expectation of the level of mechanical work involved in this mechanism led us to hypothesize that the metabolic cost of breathing is higher in birds than in other tetrapods. To test this theory, we used unidirectional artificial ventilation (UDV) to stop normal ventilatory movements in guinea fowl (Numida meleagris L.) at rest and during treadmill locomotion at three speeds. Oxygen consumption was measured during normal breathing and UDV, and the difference was used to approximate the cost of ventilation. Contrary to our prediction, metabolism increased when ventilatory movements ceased during UDV at rest. Although we do not understand why this occurred we suspect that UDV induced a homeostatic mechanism to counteract the loss of carbon dioxide. Nevertheless, across all running speeds, metabolism decreased significantly with UDV, indicating a minimum cost of ventilation during running of 1.43+/-0.62% of total running metabolism or 0.48+/-0.21 mL O(2) (L ventilated)(-1). These results suggest that the metabolic cost of ventilation is low in birds and that it is within the range of costs reported previously for other amniotes.
鸟类高度特化的肺部通气机制依赖于胸骨和腹部内脏的背腹向运动。我们对这种机制所涉及的机械功水平的预期，使我们假设鸟类的呼吸代谢成本高于其他四足动物。为了验证这一理论，我们使用单向人工通气（UDV）在休息和三种速度的跑步机运动中停止珍珠鸡（Numida meleagris L.）的正常通气运动。在正常呼吸和 UDV 期间测量耗氧量，并将差异用于近似通气成本。与我们的预测相反，在 UDV 休息时停止通气运动时代谢增加。虽然我们不明白为什么会这样，但我们怀疑 UDV 诱导了一种体内平衡机制来对抗二氧化碳的丧失。尽管如此，在所有跑步速度下，UDV 都会导致代谢显著下降，这表明跑步时的最低通气成本为 1.43+/-0.62%的总跑步代谢或 0.48+/-0.21 毫升 O2（通气量）-1。这些结果表明，鸟类的通气代谢成本较低，并且在先前报道的其他羊膜动物的成本范围内。
