Duke Jeffrey T, Ultsch Gordon R
Department of Biology, University of Alabama, 35487, Tuscaloosa, AL, USA.
Oecologia. 1990 Aug;84(1):16-23. doi: 10.1007/BF00665589.
The giant salamanders of North America include 4 genera, all of which are aquatic. We have compared the efficacy of aquatic O uptake among them by measuring theVO while submerged and determining the responses to progressive hypoxia at 10-240 mmHg at 20° C. Both species ofAmphiuma were metabolic O conformers over the entire range ofPO. About half ofSiren lacertina were conformers over this range, and half were regulators with an average critical O tension of 92 mmHg. There were no short-term changes (days) in the response ofSiren to progressive hypoxia, but one animal switched from conformation to regulation after 4-5 months. Neither genus is considered to have an exceptionally low metabolic rate. The "whole-body O conductance", defined asΔVO/ΔPO(µl O · g · h · mmHg) in the range of metabolic O conformity, was least in the species most dependent upon air-breathing and most likely to be found in hypoxic waters (e.g., 0.076 forAmphiuma), and greatest in those that airbreathe less frequently and/or are found in relatively normoxic waters (e.g., 0.429 forNecturus). These conductances are considered to be adaptive in terms of preventing O loss through the skin, or in facilitating its uptake, as correlated with the O tensions normally prevailing in the environment of each species.
北美大鲵包括4个属，均为水生动物。我们通过测量它们在水下时的耗氧量（VO）并确定在20℃下10 - 240 mmHg的渐进性低氧环境中的反应，比较了它们对水中氧气摄取的效率。在整个PO范围内，两种鳗螈属动物均为代谢性氧顺应者。在这个范围内，约一半的斑泥螈是顺应者，另一半是调节者，其平均临界氧张力为92 mmHg。斑泥螈对渐进性低氧的反应在短期内（数天）没有变化，但有一只动物在4 - 5个月后从顺应状态转变为调节状态。这两个属都不被认为具有特别低的代谢率。在代谢性氧顺应范围内定义为ΔVO/ΔPO（µl O·g·h·mmHg）的“全身氧传导率”，在最依赖空气呼吸且最可能出现在缺氧水域的物种中最低（例如，鳗螈属为0.076），而在那些较少进行空气呼吸和/或出现在相对正常氧环境水域的物种中最高（例如，泥螈属为0.429）。这些传导率被认为在防止通过皮肤的氧气损失或促进其摄取方面具有适应性，这与每个物种环境中通常存在的氧张力相关。
