Aldosterone regulates Na,K-ATPase and increases lung edema clearance in rats

Aldosterone increases the Na,K-ATPase function in renal cells involved in active Na(+) transport. Because the alveolar type 2 (AT2) cells participate in active Na(+) transport, we studied whether aldosterone regulates the Na,K-ATPase in rat AT2 cells and whether aldosterone delivered by aerosols to spontaneously breathing rats affects edema clearance in a model of isolated-perfused lungs. The AT2 cells treated with aldosterone had increased Na,K-ATPase beta1-subunit mRNA and protein, which was associated with a 4-fold increase in the Na,K-ATPase hydrolytic activity and the ouabain-sensitive (86)Rb(+) uptake. In physiologic experiments, 24 h after aldosterone was delivered by aerosols to the rat air spaces, the active Na(+) transport and lung edema clearance increased by approximately 53% as compared with control rats and rats in which saline aerosols were delivered. The data suggest that increased active Na(+) transport and lung edema clearance induced by aldosterone is probably due to Na,K-ATPase regulation in alveolar epithelial cells. Conceivably, aldosterone may be used as a strategy to increase lung edema clearance.