Gilmour K M, Perry S F
Department of Biology and Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, ON, Canada.
J Exp Biol. 2009 Jun;212(Pt 11):1647-61. doi: 10.1242/jeb.029181.
Carbonic anhydrase (CA) is the zinc metalloenzyme that catalyses the reversible reactions of CO(2) with water. CA plays a crucial role in systemic acid-base regulation in fish by providing acid-base equivalents for exchange with the environment. Unlike air-breathing vertebrates, which frequently utilize alterations of breathing (respiratory compensation) to regulate acid-base status, acid-base balance in fish relies almost entirely upon the direct exchange of acid-base equivalents with the environment (metabolic compensation). The gill is the critical site of metabolic compensation, with the kidney playing a supporting role. At the gill, cytosolic CA catalyses the hydration of CO(2) to H(+) and HCO(3)(-) for export to the water. In the kidney, cytosolic and membrane-bound CA isoforms have been implicated in HCO(3)(-) reabsorption and urine acidification. In this review, the CA isoforms that have been identified to date in fish will be discussed together with their tissue localizations and roles in systemic acid-base regulation.
碳酸酐酶（CA）是一种锌金属酶，催化二氧化碳与水的可逆反应。通过提供酸碱当量与环境进行交换，CA在鱼类的全身酸碱调节中起着至关重要的作用。与经常利用呼吸变化（呼吸补偿）来调节酸碱状态的空气呼吸脊椎动物不同，鱼类的酸碱平衡几乎完全依赖于与环境直接交换酸碱当量（代谢补偿）。鳃是代谢补偿的关键部位，肾脏起辅助作用。在鳃中，胞质CA催化二氧化碳水合形成氢离子和碳酸氢根离子，以便排出到水中。在肾脏中，胞质和膜结合的CA同工型与碳酸氢根重吸收和尿液酸化有关。在这篇综述中，将讨论迄今为止在鱼类中已鉴定出的CA同工型，以及它们在组织中的定位和在全身酸碱调节中的作用。
