Developmental regulation of Na,K-ATPase in rat lung

David H. Ingbar, Cynthia Burns Weeks, Maureen Gilmore-Hebert, Eric Jacobsen, Sara Duvick, Richard Dowin, S. Kay Savik, James D. Jamieson

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Late in gestation lung epithelium changes from net chloride and fluid secretion to sodium and fluid absorption. Fluid resorption is required for postnatal gas exchange and occurs by combined action of epithelial sodium channels and Na,K-ATPase. We hypothesized that alveolar epithelial Na,K-ATPase increases perinatally. Immunofluorescence (IF) and immunoelectron microscopy (IEM) with a monoclonal anti-α subunit antibody demonstrated that Na,K-ATPase was present on the basolateral surfaces of columnar epithelial cells at fetal day (FD) 17 and on type II cells throughout development. However, type I epithelial cells did not have detectable Na,K-ATPase. The steady-state levels of both the α1 isoform and β-subunit mRNAs were maximal at FD20-neonatal day (ND) 1, with consistent increases from the FD17 level. Na,K-ATPase α-subunit protein also increased from FD17 to FD20-22 and then decreased in the early postnatal period. The ouabain-inhibitable sodium pump activity per milligram membrane protein increased 2.6-fold from FD17 to FD22-ND1 (P < 0.05). The quantities of sodium pump mRNA, antigenic protein, and enzyme activity increase in late gestation in accord with a proposed role for Na,K-ATPase in resorption of alveolar sodium and fluid in preparation for birth.

Original languageEnglish (US)
Pages (from-to)L619-L629
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume270
Issue number4 14-4
DOIs
StatePublished - Apr 1996

Keywords

  • Alveolar development
  • Alveolar epithelium
  • Sodium pump
  • Sodium transport

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