Wells R M, Tetens V, Brittain T
Nature. 1983;306(5942):500-2. doi: 10.1038/306500a0.
It is generally accepted that the sigmoidal nature of the haemoglobin-oxygen dissociation curve (ODC) is necessary for efficient oxygen transport in terrestrial vertebrates because it allows large volumes of oxygen to be bound or released for relatively small changes in the partial pressure of oxygen (PO2) in the blood. Furthermore, the amount of oxygen to tissues is increased by hydrogen ions produced from the dissociation of carbon dioxide in solution. The generality of these key features of cooperative oxygen binding and the Bohr effect holds for reptiles, birds and mammals, including representatives with special respiratory requirements for diving, burrowing and living at high altitude. Sphenodon punctatus is the sole surviving representative of the ancient order of 'beakhead' reptiles (order Rhynchocephalia) which were once widely distributed during the Triassic period before the spectacular radiation of dinosaur faunas. We have now investigated the oxygen transporting properties of blood from Sphenodon and find that the ODC is hyperbolic, with a high affinity for oxygen and very small Bohr effect. This combination of characteristics is unique among terrestrial vertebrates and accords with a low demand for oxygen and limited scope for aerobic activity.
人们普遍认为，血红蛋白 - 氧解离曲线（ODC）的S形特性对于陆地脊椎动物高效运输氧气是必要的，因为它能使血液中氧分压（PO2）相对较小的变化就能结合或释放大量氧气。此外，溶液中二氧化碳解离产生的氢离子会增加输送到组织的氧气量。协同氧结合和波尔效应的这些关键特性普遍适用于爬行动物、鸟类和哺乳动物，包括对潜水、挖掘和在高海拔生活有特殊呼吸需求的物种。斑点楔齿蜥是古老的“喙头”爬行动物目（喙头目）唯一现存的代表，在恐龙动物群大规模辐射之前的三叠纪时期，该目曾广泛分布。我们现在研究了斑点楔齿蜥血液的氧运输特性，发现其ODC是双曲线型的，对氧气具有高亲和力且波尔效应非常小。这种特性组合在陆地脊椎动物中是独一无二的，与低氧需求和有限的有氧活动范围相一致。
