Acid-base homeostasis is critical to maintenance of normal health. Renal ammonia excretion is the quantitatively predominant component of renal net acid excretion, both under basal conditions and in response to acid-base disturbances. Although titratable acid excretion also contributes to renal net acid excretion, the quantitative contribution of titratable acid excretion is less than that of ammonia under basal conditions and is only a minor component of the adaptive response to acid-base disturbances. In contrast to other urinary solutes, ammonia is produced in the kidney and then is selectively transported either into the urine or the renal vein. The proportion of ammonia that the kidney produces that is excreted in the urine varies dramatically in response to physiological stimuli, and only urinary ammonia excretion contributes to acid-base homeostasis. As a result, selective and regulated renal ammonia transport by renal epithelial cells is central to acid-base homeostasis. Both molecular forms of ammonia, NH3 and NH4+, are transported by specific proteins, and regulation of these transport processes determines the eventual fate of the ammonia produced. In this review, we discuss these issues, and then discuss in detail the specific proteins involved in renal epithelial cell ammonia transport.

中文翻译：

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氨转运蛋白及其在酸碱平衡中的作用。

酸碱稳态对于维持正常健康至关重要。在基础条件下以及对酸碱紊乱的响应中，肾氨排泄是肾脏净酸排泄的定量主要成分。尽管可滴定的酸排泄也有助于肾脏的净酸排泄，但在基础条件下可滴定的酸排泄的定量贡献小于氨的定量贡献，并且仅是对酸碱紊乱的适应性反应的次要组成部分。与其他尿溶质相反，氨在肾脏中产生，然后选择性地转运到尿液或肾静脉中。肾脏产生的氨在尿液中排泄的比例会因生理刺激而异，并且只有尿中的氨排泄才有助于酸碱稳态。结果，肾上皮细胞选择性和调节肾氨转运是酸碱稳态的关键。氨的两种分子形式，即NH3和NH4 +，都是由特定的蛋白质转运的，这些转运过程的调节决定了最终产生的氨的命运。在这篇综述中，我们讨论了这些问题，然后详细讨论了涉及肾上皮细胞氨转运的特定蛋白。