Alveolar epithelial barrier - Role in lung fluid balance in clinical lung injury

This article reviews new insights into the basic mechanisms that regulate vectorial transport of salt and water across the alveolar epithelium of the adult lung. The authors provide evidence that active ion (sodium) transport is the primary mechanism that regulates in vivo alveolar fluid clearance and discuss how catecholamine-dependent and independent mechanisms can upregulate alveolar transport. The authors briefly discuss evidence that implicates transcellular water channels in alveolar epithelial fluid transport. Finally, the authors discuss the transport function of the alveolar epithelial barrier under pathologic conditions that are relevant to clinical pulmonary edema and acute respiratory distress syndrome.