title: Ammonium transport in the kidney.
abstract: 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 luminal 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 NH3 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.
authors.affiliation: UPMC University of Paris 06; and INSERM UMRS 872 Team 3; CNRS ERL7226, Laboratory of Renal Genomics, Physiology and Physiopathology, Centre de recherche des Cordeliers, Paris, France. dominique.eladari@crc.jussieu.fr
authors.forename: Dominique
authors.initials: D
authors.lastname: Eladari
authors.forename: Régine
authors.initials: R
authors.lastname: Chambrey
mesh_terms: D000818:Animals; D006801:Humans; D017136:Ion Transport; D007668:Kidney / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D008138:Loop of Henle / Q000378:metabolism; D051379:Mice; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*
chemical_list: D000644:Quaternary Ammonium Compounds