Abstract: Objective To evaluate the capacity of active water and sodium transport of alveolar type Ⅱ (AT Ⅱ) cells in rats with acute respiratory distress syndrome (ARDS). Methods AT Ⅱcells were isolated and purified from rats with ARDS, and the distribution of aquaporin-1 (AQP-1) on the cells was observed by immunocytochemistry, immunoelectron microscopy and Western blotting. The sodium currents were detected by patch-clamp technique in whole-cell recording mode. Results Immunocytochemistry showed staining for AQP-1 in rat ATⅡcells, and immunoelectron microscope demonstrated the presence of AQP-1, which was decreased as shown by Western blotting in comparison with the control group. The whole-cell currents were also decreased, but remained sensitive to terbutalin treatment. Conclusions The capacity of active water and sodium transport is damaged, but not totally lost in ATⅡ cells of ARDS rats. Terbutalin can increase the currents even if in pathological conditions. AQP-1 and sodium transport of ATⅡ cells play an important role in pulmonary liquid clearance.