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This Article Full Text Full Text (PDF) All Versions of this Article: 296/6/L1051    most recent 00021.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by DeMaio, L. Articles by Borok, Z. PubMed PubMed Citation Articles by DeMaio, L. Articles by Borok, Z.

Characterization of mouse alveolar epithelial cell monolayers

¹Department of Medicine, Will Rogers Institute Pulmonary Research Center, and ²Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, California; and ³Department of Internal Medicine, Washington University, St. Louis, Missouri

Submitted 21 January 2009 ; accepted in final form 20 March 2009

We investigated the influence of extracellular matrix on transport properties of mouse alveolar epithelial cell (AEC) monolayers (MAECM) and transdifferentiation of isolated mouse alveolar epithelial type II (AT2) cells into an alveolar epithelial type I (AT1) cell-like phenotype. Primary mouse AT2 cells plated on laminin 5-coated polycarbonate filters formed monolayers with transepithelial resistance (R_T) and equivalent short-circuit current (I_EQ) of 1.8 k·cm² and 5.3 µA/cm², respectively, after 8 days in culture. Amiloride (10 µM), ouabain (0.1 mM), and pimozide (10 µM) decreased MAECM I_EQ to 40%, 10%, and 65% of its initial value, respectively. Sequential addition of pimozide and amiloride, in either order, revealed that their inhibitory effects are additive, suggesting that cyclic nucleotide-gated channels contribute to amiloride-insensitive active ion transport across MAECM. Ussing chamber measurements of unidirectional ion fluxes across MAECM under short-circuit conditions indicated that net absorption of Na⁺ in the apical-to-basolateral direction is comparable to net ion flux calculated from the observed short-circuit current: 0.38 and 0.33 µeq·cm^–2·h^–1, respectively. Between days 1 and 9 in culture, AEC demonstrated increased expression of aquaporin-5 protein, an AT1 cell marker, and decreased expression of pro-surfactant protein-C protein, an AT2 cell marker, consistent with transition to an AT1 cell-like phenotype. These results demonstrate that AT1 cell-like MAECM grown on laminin 5-coated polycarbonate filters exhibit active and passive transport properties that likely reflect the properties of intact mouse alveolar epithelium. This mouse in vitro model will enhance the study of AEC derived from mutant strains of mice and help define important structure-function correlations.

alveolar epithelium; ion transport; short-circuit current; transepithelial resistance; phenotypic transition

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