Role of sodium/hydrogen exchanger isoform NHE3 in fluid secretion and absorption in mouse and rat cholangiocytes

Albert Mennone, Daniel Biemesderfer, Daniel Negoianu, Chao Ling Yang, Thecla Abbiati, Patrick J. Schultheis, Gary E. Shull, Peter S. Aronson, James L. Boyer

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

Na+/H+ exchanger (NHE) isoforms play important roles in intracellular pH regulation and in fluid absorption. The isoform NHE3 has been localized to apical surfaces of epithelia and in some tissues may facilitate the absorption of NaCl. To determine whether the apical isoform NHE3 is present in cholangiocytes and to examine whether it has a functional role in cholangiocyte fluid secretion and absorption, immunocytochemical studies were performed in rat liver with NHE3 antibodies and functional studies were obtained in isolated bile duct units from wild-type and NHE3 (-/-) mice after stimulation with forskolin, using video-microscopic techniques. Our results indicate that NHE3 protein is present on the apical membranes of rat cholangiocytes and on the canalicular membrane of hepatocytes. Western blots also detect NHE3 protein in rat cholangiocytes and isolated canalicular membranes. After stimulation with forskolin, duct units from NHE3 (-/-) mice fail to absorb the secreted fluid from the cholangiocyte lumen compared with control animals. Similar findings were observed in isolated bile duct units from wild-type mice and rats in the presence of the Na+/H+ exchanger inhibitor 5-(N-ethyl-N-isopropyl)-amiloride. In contrast, we could not demonstrate absorption of fluid from the canalicular lumen of mouse or rat hepatocyte couplets after stimulation of secretion with forskolin. These findings indicate that NHE3 is located on the apical membrane of rat cholangiocytes and that this NHE isoform can function to absorb fluid from the lumens of isolated rat and mouse cholangiocyte preparations.

Original languageEnglish (US)
Pages (from-to)G247-G254
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume280
Issue number2 43-2
DOIs
StatePublished - Feb 2001

Keywords

  • Bile duct epithelium
  • Bile secretion
  • Hepatocyte

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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