Functional significance of intestinal Na+-K+-ATPase: In vivo ouabain inhibition

A. N. Charney, M. Donowitz

Research output: Contribution to journalArticlepeer-review

Abstract

A role for Na+-K+-activated adenosine triphosphatase (Na-K-ATPase) in intestinal sodium and water absorption under basal conditions has not been demonstrated in vivo. To delineate this role, adjacent rabbit ileal loops were simultaneously perfused in vivo with a Ringer-HCO3 solution. The perfusate was then changed in one of the loops to a Ringer-HCO3 solution containing ouabain. After the perfusion, each loop was assayed for Na-K-ATPase and Mg-ATPase activities. Perfusion with 19.2 mM ouabain produced net sodium and water secretion and a 32% reduction in Na-K-ATPase activity. Ouabain perfusion did not alter the activity of Mg-ATPase or affect histology. When a Ringer-HCO3 solution containing 15 mM glucose was perfused, ouabain reduced glucose absorption by 50%. As predicted from the known competition between ouabain and potassium for a Na-K-ATPase receptor site in vitro, ouabain-induced intestinal secretion and Na-K-ATPase inhibition could be reversed with a Ringer-HCO3 solution containing 25 mM KCl. These results suggest that: mucosal Na-K-ATPase plays an important role in the ileal absorption of sodium, glucose, and water under basal conditions; and that an underlying intestinal secretory process exists as revealed by the selective in vivo inhibition of intestinal absorption.

Original languageEnglish (US)
Pages (from-to)E629-E636
JournalAmerican Journal of Physiology Endocrinology Metabolism and Gastrointestinal Physiology
Volume3
Issue number6
DOIs
StatePublished - 1978
Externally publishedYes

ASJC Scopus subject areas

  • Medicine(all)

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