Na+/H+ exchange mediates postprandial ileal water and electrolyte transport.
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.
Hines
O J
OJ
Department of Surgery, UCLA Medical Center, USA.
Bilchik
A J
AJ
McFadden
D W
DW
Rodgers
P J
PJ
Bautista
N
N
Zinner
M J
MJ
Ashley
S W
SW
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*
D002712:Chlorides; D004573:Electrolytes; D017923:Sodium-Hydrogen Exchangers; D014867:Water; D000584:Amiloride; D012964:Sodium