title: Inhibition of the sodium/hydrogen antiport by ammonium ion.
abstract: OBJECTIVE
  Previous work from our laboratory suggests that one mechanism of ammonium transport across the intestinal membrane may be substitution of ammonium for sodium in the sodium/hydrogen antiport. This study further supports this mechanism by demonstrating an inhibitory role for ammonium in the sodium/hydrogen exchange.
  
  
  METHODS
  Whole brush border intestinal enterocytes were studied, incorporating a fluorescent marker for sodium transport. The kinetics of the effect of ammonium on sodium transport were determined.
  
  
  RESULTS
  Ammonium is an inhibitor of sodium in the sodium/hydrogen exchanger. Quantitatively, the inhibition appears to be competitive.
  
  
  CONCLUSIONS
  The inhibitory effect of ammonium on sodium/hydrogen exchange supports a mechanism of ionized ammonium transport where it substitutes for sodium in the sodium/ hydrogen exchanger. This is a mechanism by which hyperchloremic metabolic acidosis occurs following urinary intestinal diversion.
authors.affiliation: Department of Urology, Massachusetts General Hospital, Boston 02114, USA.
authors.forename: D S
authors.initials: DS
authors.lastname: Stampfer
authors.forename: W S
authors.initials: WS
authors.lastname: McDougal
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D007421:Intestine, Small / Q000648:ultrastructure; D008297:Male; D008871:Microvilli / Q000502:physiology; D000644:Quaternary Ammonium Compounds / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors*
chemical_list: D000644:Quaternary Ammonium Compounds; D017923:Sodium-Hydrogen Exchangers