Early postirradiation changes in Na⁺ and fluid transport across alveolar epithelium in rats

To study changes in Na⁺ and fluid transport that occur soon after irradiation of the thorax, we used fluid-filled isolated rat lungs. Irradiation 15 Gy of ⁶⁰Co doubled the fluid absorption rate across the alveolar epithelium within 2 weeks, but fluid absorption had returned to the baseline values by 3 weeks after irradiation. The timing of this change in fluid absorption was parallel to the time course of Na⁺ escape across alveolar epithelium and the two correlated closely. These data suggest that a dysfunction of alveolar epithelial Na⁺ transport is involved in the development of pulmonary edema after irradiation of the thorax.