Suarez R K, Brown G S, Hochachka P W
Am J Physiol. 1986 Sep;251(3 Pt 2):R537-42. doi: 10.1152/ajpregu.1986.251.3.R537.
It has been known for some two decades that hovering flight in hummingbirds is the most energetically expensive muscle work known among vertebrates, but the metabolic support for such work has never been clarified. Measurement of the maximum activities of key enzymes of carbohydrate, fat, and amino acid catabolism in flight muscle and heart of rufous hummingbirds (Selasphorus rufus) reveals that the high ATP requirements of short-term hovering flight can only be supported by the oxidation of carbohydrate. Fat oxidation can support a substantially lower maximum rate of ATP turnover, indicating that this process can power only the lower +.++energetic requirements of long-term forward or migratory flight. Mitochondria isolated from flight muscle oxidize pyruvate and palmitoyl-CoA equally well. The inhibition of pyruvate oxidation by palmitoyl-CoA oxidation provides a mechanism by which fat oxidation inhibits carbohydrate oxidation in the transition from short- to long-term flight.
大约二十年来，人们一直知道蜂鸟的悬停飞行是脊椎动物中已知的能量消耗最昂贵的肌肉活动，但这种活动的代谢支持从未得到阐明。对棕煌蜂鸟（Selasphorus rufus）飞行肌肉和心脏中碳水化合物、脂肪和氨基酸分解代谢关键酶的最大活性进行测量后发现，短期悬停飞行对ATP的高需求只能通过碳水化合物的氧化来支持。脂肪氧化只能支持低得多的最大ATP周转率，这表明该过程只能满足长期向前飞行或迁徙飞行中较低的能量需求。从飞行肌肉中分离出的线粒体对丙酮酸和棕榈酰辅酶A的氧化效果同样良好。棕榈酰辅酶A氧化对丙酮酸氧化的抑制作用提供了一种机制，通过这种机制，在从短期飞行到长期飞行的转变过程中，脂肪氧化会抑制碳水化合物氧化。
