Localization of the epithelial sodium channel subunit mrnas in
adult rat lung by in situ hybridization.
Matsushita, K., P. B. McCray, R. D. Sigmund, M. J. Welsh, J. B.
Stokes.
Departments of Internal Medicine, Pediatrics, Physiology and
Biophysics, Howard Hughes Medical Institute, and the Department of
Veteran's Affairs Medical Center, University of Iowa College of
Medicine, Iowa City, IA 52242
APStracts 3:0061L, 1996.
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 (a, b, and [gamma]rENaC). By
Northern blot all 3 subunit mRNAs were expressed in adult rat lung.
Each subunit was expressed as a single transcript of 3.7, 2.2 and 3.2
kb for a, b, and [gamma]rENaC, respectively. To localize the a, b,
and [gamma]rENaC subunit mRNAs we used in situ hybridization. Frozen
and paraffin embedded tissues were hybridized with sense and
antisense 35S 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 ENaC playing an important role in the absorption of
Na+ and fluid across the pulmonary epithelium in all regions of the
lung.
Received 4 January 1996; accepted in final form 3 April 1996.
APS Manuscript Number L4-6.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 May 96