highlighted topics Lung Edema Clearance: 20 Years of Progress Invited Review: Lung edema clearance: role of Na-K-ATPase

respiratory failure is a consequence of edema accumulation due to elevation of pulmonary capillary pressures and/or increases in perme-ability of the alveolocapillary barrier. It has been recognized that lung edema clearance is distinct from edema accumulation and is largely effected by active Na transport out of the alveoli rather than reversal of the Starling forces, which control liquid flux from the pulmonary circu-lation into the alveolus. The alveolar epithelial Na-K-ATPase has an important role in regulating cell integrity and homeostasis. In the last 15 yr, Na-K-ATPase has been localized to the alveolar epithelium and its contribution to lung edema clearance has been appreciated. The impor-tance of the alveolar epithelial Na-K-ATPase function is reflected in the changes in the lung’s ability to clear edema when the Na-K-ATPase is inhibited or increased. An important focus of the ongoing research is the study of the mechanisms of Na-K-ATPase regulation in the alveolar epithelium during lung injury and how to accelerate lung edema clearance by modulating Na-K-ATPase activity. acute respiratory distress syndrome; alveolar epithelium; ion transport RESOLUTION OF PULMONARY EDEMA occurs as the result of active Na transport across the alveolar epithelium via apical amiloride-sensitive Na channels and basolat-eral Na-K-ATPases (19, 41, 57). This active vectorial Na flux produces a transepithelial osmotic gradient that causes water to passively move from the air spaces to the alveolar interstitium. In some models of acute lung injury and in patients with acute respiratory distress syndrome (ARDS), the lung’s ability to clea