Active transport in the alveolar epithelium of the adult lung: vestigial or vital?
Active secretion by mammalian fetal pulmonary alveolar epithelium is well recognized, as is the role of the adult epithelium in the secretion of surfactant. Recent studies have demonstrated active absorption by adult epithelium involving two sodium-dependent pathways. This finding has focused attention on how poorly we understand both the disposition of alveolar liquid and the physiological role of surfactant. In this paper we review the evidence that the adult mammalian alveolar epithelium absorbs solutes by active transport, and we assess the physiological importance of the resulting liquid movements.
D000818:Animals; D001693:Biological Transport, Active; D002478:Cells, Cultured; D004848:Epithelium / Q000378:metabolism; D018495:Fluid Shifts / Q000502:physiology; D066298:In Vitro Techniques; D008322:Mammals; D011650:Pulmonary Alveoli / Q000378:metabolism*