Lung edema clearance:: 20 years of progress invited review:: Lung edema clearance:: role of Na+-K+-ATPase

Acute hypoxemic respiratory failure is a consequence of edema accumulation due to elevation of pulmonary capillary pressures and/or increases in permeability 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 circulation 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 importance 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.