Na+/H+ exchange mediates postprandial ileal water and electrolyte transport

• Published in: Digestive diseases and sciences 1995-04, Vol.40 (4), p.774-780
• Main Authors: HINES, O. J, BILCHIK, A. J, MCFADDEN, D. W, RODGERS, P. J, BAUTISTA, N, ZINNER, M. J, ASHLEY, S. W
• Format: Article
• Language: English
• Subjects: Amiloride - pharmacology; Animals; Biological and medical sciences; Chlorides - metabolism; Dogs; Dose-Response Relationship, Drug; Electrolytes - metabolism; Female; Fundamental and applied biological sciences. Psychology; Ileum - metabolism; Intestinal Absorption; Intestine. Mesentery; Jejunum - metabolism; Sodium - metabolism; Sodium-Hydrogen Exchangers - antagonists & inhibitors; Sodium-Hydrogen Exchangers - physiology; Vertebrates: digestive system; Water - metabolism
• ISSN: 0163-2116; 1573-2568
• DOI: 10.1007/BF02064978

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.