科研之友
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摘要
Ammonium excretion into the urine is the main mechanism of renal acid excretion. Ammonium is produced by epithelial cells of the proximal tubule and then secreted into the lumina! fluid. However, before its final excretion into urine, ammonium ion is reabsorbed by the thick ascending limb (TAL), and accumulated in the interstitium to build up a corticopapillary gradient of ammonium which is necessary for the final diffusion of the gas NH3 in parallel to active proton secretion. Recent evidence has been provided by the study of several mouse models of renal acidosis. Particularly, it has been shown that the Na(+)/H(+) exchanger NHE4 is a critical step of ammonium absorption by the TAL, and also that NH(3) diffusion across the membrane of collecting duct cells requires the presence of the recently identified gas channel Rhcg. This review is an update on the different mechanisms of ammonium transport, along the nephron, with a particular emphasis on these new molecules.
- 出版日期2010-12
