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 |
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Format: | Artikel |
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 |
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ISSN: | 1040-0605 1522-1504 |
DOI: | 10.1152/ajplung.00130.2000 |