title: Na+/H+ exchange mediates postprandial ileal water and electrolyte transport.
abstract: Feeding stimulates fluid and electrolyte absorption in the small intestine. Previous studies have suggested that Na+/glucose cotransport is important in initiating this response in the jejunum. The purpose of this study was to determine whether Na+/H+ exchange plays a role in meal-induced absorption. Exteriorized, neurovascularly intact jejunal and ileal loops (25 cm) were constructed in dogs. Following a two-week period of postoperative recovery, the loops of awake dogs were perfused with standard buffer alone or with increasing concentrations of amiloride, a Na+/H+ exchange inhibitor. Water, sodium, and chloride fluxes were calculated following a meal using [14C]PEG as a volume marker. The meal significantly increased absorption in both the jejunum (P < 0.001) and ileum (P < 0.01) in those animals perfused with buffer alone. More significantly, amiloride suppressed the increased absorption seen following a meal in the ileum (P < 0.001) but not the jejunum. The response in the ileum was dose dependent. These findings suggest that a major mediator of postprandial sodium and water absorption in the ileum is the Na+/H+ exchanger.
authors.affiliation: Department of Surgery, UCLA Medical Center, USA.
authors.forename: O J
authors.initials: OJ
authors.lastname: Hines
authors.forename: A J
authors.initials: AJ
authors.lastname: Bilchik
authors.forename: D W
authors.initials: DW
authors.lastname: McFadden
authors.forename: P J
authors.initials: PJ
authors.lastname: Rodgers
authors.forename: N
authors.initials: N
authors.lastname: Bautista
authors.forename: M J
authors.initials: MJ
authors.lastname: Zinner
authors.forename: S W
authors.initials: SW
authors.lastname: Ashley
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002712:Chlorides / Q000378:metabolism; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004573:Electrolytes / Q000378:metabolism*; D005260:Female; D007082:Ileum / Q000378:metabolism*; D007408:Intestinal Absorption; D007583:Jejunum / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors / Q000502:physiology*; D014867:Water / Q000378:metabolism*
chemical_list: D002712:Chlorides; D004573:Electrolytes; D017923:Sodium-Hydrogen Exchangers; D014867:Water; D000584:Amiloride; D012964:Sodium