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Journal of Biomedicine and Biotechnology
Volume 2011, Article ID 174306, 16 pages
http://dx.doi.org/10.1155/2011/174306
Review Article

Ion Transport by Pulmonary Epithelia

Institute of Animal Physiology, Justus Liebig University Giessen, Wartweg 95, 35392 Giessen, Germany

Received 1 July 2011; Accepted 16 August 2011

Academic Editor: Frederick D. Quinn

Copyright © 2011 Monika I. Hollenhorst et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The lung surface of air-breathing vertebrates is formed by a continuous epithelium that is covered by a fluid layer. In the airways, this epithelium is largely pseudostratified consisting of diverse cell types such as ciliated cells, goblet cells, and undifferentiated basal cells, whereas the alveolar epithelium consists of alveolar type I and alveolar type II cells. Regulation and maintenance of the volume and viscosity of the fluid layer covering the epithelium is one of the most important functions of the epithelial barrier that forms the outer surface area of the lungs. Therefore, the epithelial cells are equipped with a wide variety of ion transport proteins, among which Na+, Cl, and K+ channels have been identified to play a role in the regulation of the fluid layer. Malfunctions of pulmonary epithelial ion transport processes and, thus, impairment of the liquid balance in our lungs is associated with severe diseases, such as cystic fibrosis and pulmonary oedema. Due to the important role of pulmonary epithelial ion transport processes for proper lung function, the present paper summarizes the recent findings about composition, function, and ion transport properties of the airway epithelium as well as of the alveolar epithelium.