Localization of epithelial sodium channel subunit mRNAs in adult rat lung by in situ hybridization

Am J Physiol. 1996 Aug;271(2 Pt 1):L332-9. doi: 10.1152/ajplung.1996.271.2.L332.


The transport of Na+ through amiloride-sensitive sodium channels (ENaC) plays a major role in the absorption of fluid across the pulmonary epithelium. The proteins forming the ENaC channel are encoded by three genes in the rat (alpha-, beta-, and gamma-rENaC). According to Northern blot, all three subunit mRNAs were expressed in adult rat lung. Each subunit was expressed as a single transcript of approximately 3.7, 2.2, and 3.2 kb for alpha-, beta-, and gamma-rENaC, respectively. To localize the alpha-, beta-, and gamma-rENaC subunit mRNAs, we used in situ hybridization. Frozen and paraffin-embedded tissues were hybridized with sense and antisense 35S-labeled riboprobes. The alpha-rENaC mRNA was most abundant and was expressed diffusely in epithelia of the trachea, bronchi, bronchioles, and alveoli. At the alveolar level, alpha-rENaC was expressed in type II cells. The beta- and gamma-rENaC mRNAs were most abundant in the bronchial and bronchiolar epithelia. All three subunits were expressed in the renal cortical collecting duct in a pattern similar to that previously reported by other investigators. Thus the rENaC subunit mRNAs are expressed in regions of the lung where functional Na+ absorption is found. These results are consistent with an important role for ENaC in the absorption of Na+ and fluid across the pulmonary epithelium in all regions of the lung.

Publication types

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

MeSH terms

  • Animals
  • Base Sequence
  • Blotting, Northern
  • Epithelium / metabolism
  • In Situ Hybridization
  • Kidney / metabolism
  • Lung / metabolism*
  • Molecular Probes / genetics
  • Molecular Sequence Data
  • Polymerase Chain Reaction
  • RNA, Messenger / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Sodium Channels / genetics*
  • Tissue Distribution
  • Transcription, Genetic


  • Molecular Probes
  • RNA, Messenger
  • Sodium Channels