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Hyperoxia Increases Active Alveolar Na+ Resorption in Vivo and Type II Cell Na, K-ATPase in Vitro

1994; Elsevier BV; Volume: 105; Issue: 3 Linguagem: Inglês

10.1378/chest.105.3_supplement.75s

1931-3543

Ethan P. Carter, Echerki Sara, Christine Wendt, Jordan Dunitz, Linda Nici, O. Douglas Wangensteen, David H. Ingbar,

Asthma and respiratory diseases

Alveoli must be kept free of fluid for effective gas exchange to occur. The alveolar epithelium is a tight epithelium, 1 Cheek JM Kim KJ Crandall ED Tight monolayers of rat alveolar epithelial cells: bioelectric properties and active sodium transport. Am J Physiol. 1989; 256: C688-93 PubMed Google Scholar , 2 Saumon G Basset G Electrolyte and fluid transport across the mature alveolar epithelium. J Appl Physiol. 1993; 74: 1-15 Crossref PubMed Scopus (119) Google Scholar and although small amounts of fluid and solute leak into the alveoli, the alveoli are kept relatively dry. In situ and in isolated lungs, active sodium transport from the alveoli to the pulmonary interstitium establishes an osmotic gradient that removes fluid from the alveoli. 3 Basset G Crone C Saumon G Significance of active ion transport in transalveolar water absorption: a study on isolated rat lung. J Physiol. 1987; 384: 311-324 Crossref PubMed Scopus (135) Google Scholar , 4 Berthiaume Y Staub NC Matthay MA Beta-adrenergic agonists increase lung liquid clearance in anesthetized sheep. J Clin Invest. 1987; 79: 335-343 Crossref PubMed Scopus (287) Google Scholar , 5 Effros RM Mason GR Hukkanen J et al. New evidence for active sodium transport from fluid-filled rat lungs. J Appl Physiol. 1989; 66: 906-919 PubMed Google Scholar The interstitial fluid can be cleared through the lymphatics or pulmonary vessels. Alveolar type II cells (ATII) probably are responsible for much of the alveolar-to-interstitial vectorial sodium transport. The evidence for this includes the following: immunolocalization of a sodium channel to the apical (alveolar) surface of ATII cells; 6 Matalon S Kirk KL Bubien JK et al. Immunocytochemical and functional characterization of Na+ conductance in adult alveolar pneumocytes. Am J Physiol. 1992; 262: C 1228-38 Google Scholar immunolocalization of Na, K-ATPase to the basolateral surface of ATII cells, but not ATI cells; 7 Nici L Dowin R Gilmore-Hebert M et al. Upregulation of rat lung Na, K-ATPase during hyperoxic injury. Am J Physiol. 1991; 261: L307-14 PubMed Google Scholar and measured apical-to-basolateral active sodium transport (ie, unidirectional ion transport, bioelectrical measurements, and "dome" formation) by ATII cell monolayers. 1 Cheek JM Kim KJ Crandall ED Tight monolayers of rat alveolar epithelial cells: bioelectric properties and active sodium transport. Am J Physiol. 1989; 256: C688-93 PubMed Google Scholar , 8 Goodman BE Crandall ED Dome formation in primary cultured monolayers of alveolar epithelial cells. Am J Physiol. 1982; 243: C96-C100 PubMed Google Scholar