Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA.
Respir Physiol Neurobiol. 2012 Dec 1;184(3):241-8. doi: 10.1016/j.resp.2012.06.002. Epub 2012 Jun 8.
Not long ago, urea was believed to freely diffuse across plasma membranes. The discovery of specialized proteins to facilitate the movement of urea across the fish gill, similar to those found in mammalian kidney, was exciting, and at the same time, perplexing; especially considering the fact that, aside from elasmobranchs, most fish do not produce urea as their primary nitrogenous waste. Increasingly, it has become apparent that many fish do indeed produce at least a small amount of urea through various processes and continued work on branchial urea transporters in teleost and elasmobranch fishes has led to recent advances in the regulation of these mechanisms. The following review outlines the substantial progress that has been made towards understanding environmental and developmental impacts on fish gill urea transport. This review also outlines the work that has been done regarding endocrine and neural control of urea excretion, most of which has been collected from only a handful of teleost fish. It is evident that more research is needed to establish the endocrine and neural control of urea excretion in fish, including fish representative of more ancient lineages (hagfish and lamprey), and elasmobranch fish.
不久前，人们认为尿素可以自由扩散穿过质膜。在鱼类鳃中发现了专门的蛋白质来促进尿素的运动，类似于在哺乳动物肾脏中发现的那些，这令人兴奋，同时也令人困惑；特别是考虑到这样一个事实，除了软骨鱼外，大多数鱼类并不将尿素作为其主要含氮废物产生。越来越明显的是，许多鱼类确实通过各种过程产生至少少量的尿素，并且对硬骨鱼和软骨鱼鳃尿素转运蛋白的持续研究导致了这些机制的调节方面的最新进展。以下综述概述了在理解环境和发育对鱼类鳃尿素转运的影响方面所取得的重大进展。该综述还概述了关于尿素排泄的内分泌和神经控制的工作，其中大部分工作仅来自少数几种硬骨鱼。显然，需要更多的研究来确定鱼类尿素排泄的内分泌和神经控制，包括更古老谱系的鱼类（七鳃鳗和盲鳗）和软骨鱼。
