Ip Y K, Chew S F
Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore, 117543, Republic of Singapore.
Prog Mol Subcell Biol. 2010;49:63-94. doi: 10.1007/978-3-642-02421-4_4.
In this chapter, up-to-date information on nitrogen metabolism and excretion in various aestivators is presented. Although aestivation involves long-term fasting and corporal torpor, adaptive responses with regard to excretory nitrogen metabolism exhibited by aestivators during aestivation differ from those exhibited by nonaestivators undergoing fasting or immobilization. Special efforts were made to address current issues pertaining to excretory nitrogen metabolism and related phenomena in aestivators. Adaptations exhibited by aestivators were discussed in relation to the induction, maintenance, and arousal phases of aestivation. For the induction phase, we included topics like urea as an internal induction signal for aestivation, alteration in the permeability of the skin to ammonia, and changes in rate of ammonia production and urea synthesis. For the maintenance phase, the emphasis was on protein synthesis and degradation, ammonia production, and urea synthesis and accumulation. For the arousal phase, the focus was on rehydration, urea excretion, and phenomena related to feeding. Adaptations exhibited by aestivators specifically to each of these three phases of aestivation are essential to the understanding of the overall aestivation process, but, at present, only limited information is available on excretory nitrogen metabolism in animals during the induction or arousal phases of aestivation. Therefore, future efforts should be made to identify adaptive responses particular to each of the three phases of aestivation in various aestivators.
在本章中，我们介绍了各种夏眠动物氮代谢和排泄的最新信息。尽管夏眠涉及长期禁食和身体蛰伏，但夏眠动物在夏眠期间表现出的排泄氮代谢适应性反应与禁食或固定不动的非夏眠动物不同。我们特别努力探讨了与夏眠动物排泄氮代谢及相关现象有关的当前问题。结合夏眠的诱导、维持和苏醒阶段，讨论了夏眠动物表现出的适应性变化。对于诱导阶段，我们涵盖了诸如尿素作为夏眠的内部诱导信号、皮肤对氨的通透性变化以及氨产生速率和尿素合成的变化等主题。对于维持阶段，重点是蛋白质合成与降解、氨产生以及尿素合成与积累。对于苏醒阶段，重点是补水、尿素排泄以及与进食相关的现象。夏眠动物针对夏眠这三个阶段各自表现出的适应性变化对于理解整个夏眠过程至关重要，但目前关于动物在夏眠诱导或苏醒阶段排泄氮代谢的信息有限。因此，未来应努力确定各种夏眠动物在夏眠三个阶段各自特有的适应性反应。
