Alveolar Epithelial Ion and Fluid Transport: Na transport proteins are expressed by rat alveolar epithelial type I cells

Will Rogers Institute Pulmonary Research Center and Division of Pulmonary and Critical Care Medicine, University of Southern California, Los Angeles, California 90033 Despite a presumptive role for type I (AT1) cells in alveolar epithelial transport, specific Na transporters have not previously been...

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Veröffentlicht in:American journal of physiology. Lung cellular and molecular physiology 2002-04, Vol.282 (4), p.599
Hauptverfasser: Borok, Zea, Liebler, Janice M, Lubman, Richard L, Foster, Martha J, Zhou, Beiyun, Li, Xian, Zabski, Stephanie M, Kim, Kwang-Jin, Crandall, Edward D
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Sprache:eng
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Zusammenfassung:Will Rogers Institute Pulmonary Research Center and Division of Pulmonary and Critical Care Medicine, University of Southern California, Los Angeles, California 90033 Despite a presumptive role for type I (AT1) cells in alveolar epithelial transport, specific Na transporters have not previously been localized to these cells. To evaluate expression of Na transporters in AT1 cells, double labeling immunofluorescence microscopy was utilized in whole lung and in cytocentrifuged preparations of partially purified alveolar epithelial cells (AEC). Expression of Na pump subunit isoforms and the -subunit of the rat (r) epithelial Na channel ( -ENaC) was evaluated in isolated AT1 cells identified by their immunoreactivity with AT1 cell-specific antibody markers (VIIIB2 and/or anti-aquaporin-5) and lack of reactivity with antibodies specific for AT2 cells (anti-surfactant protein A) or leukocytes (anti-leukocyte common antigen). Expression of the Na pump 1 -subunit in AEC was assessed in situ. Na pump subunit isoform and -rENaC expression was also evaluated by RT-PCR in highly purified (~95%) AT1 cell preparations. Labeling of isolated AT1 cells with anti- 1 and anti- 1 Na pump subunit and anti- -rENaC antibodies was detected, while reactivity with anti- 2 Na pump subunit antibody was absent. AT1 cells in situ were reactive with anti- 1 Na pump subunit antibody. Na pump 1 - and 1 - (but not 2 -) subunits and -rENaC were detected in highly purified AT1 cells by RT-PCR. These data demonstrate that AT1 cells express Na pump and Na channel proteins, supporting a role for AT1 cells in active transalveolar epithelial Na transport. alveolar epithelium; sodium pumps; ion transport; immunofluorescence; sodium channel
ISSN:1040-0605
1522-1504
DOI:10.1152/ajplung.00130.2000