Na+/H+ exchangers, NHE-1 and NHE-3, of rat intestine. Expression and localization

J Clin Invest. 1994 Jan;93(1):106-13. doi: 10.1172/JCI116933.

Abstract

Na-H exchange (NHE) is one of the major non-nutritive Na absorptive pathways of the intestine and kidney. Of the four NHE isoforms that have been cloned, only one, NHE-3, appears to be epithelial specific. We have examined the regional and cellular expression of NHE-3 in the rat intestine. NHE-3 message in the small intestine was more abundant in the villus fractions of the small intestine than in the crypts. Analysis of NHE-3 mRNA distribution in the gut by in situ hybridization demonstrated epithelial cell specificity, as well as expression preferential to villus cells. NHE-1 message, in contrast, was ubiquitous, with slightly greater expression exhibited in the differentiating crypt and lower villus cells of the small intestine. Isoform-specific NHE-3 fusion protein antibody identified a 97-kD membrane protein in the upper villus cells of the small intestine, which was exclusively localized in the apical membrane. In contrast, antibody previously developed against the COOH-terminal region of human NHE-1 (McSwine, R. L., G. Babnigg, M. W. Musch, E. B. Chang, and M. L. Villereal, manuscript submitted for publication) identified a 110-kD basolateral membrane protein. These data suggest that unlike NHE-1, which probably serves a "housekeeping" function, NHE-3 may be involved in vectorial Na transport by the intestine.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blotting, Northern
  • Carrier Proteins / analysis
  • Carrier Proteins / biosynthesis*
  • Cell Fractionation
  • Cell Membrane / metabolism
  • Cell Membrane / ultrastructure
  • Electrophoresis, Polyacrylamide Gel
  • Gene Expression*
  • In Situ Hybridization
  • Intestinal Mucosa / metabolism*
  • Intestine, Small / metabolism*
  • Male
  • Membrane Proteins / analysis
  • Membrane Proteins / isolation & purification
  • Microvilli / metabolism
  • Microvilli / ultrastructure
  • Rats
  • Rats, Sprague-Dawley
  • Sodium-Hydrogen Exchangers / analysis
  • Sodium-Hydrogen Exchangers / biosynthesis*

Substances

  • Carrier Proteins
  • Membrane Proteins
  • Sodium-Hydrogen Exchangers
  • growth factor-activatable Na-H exchanger NHE-1