Dexamethasone acutely accelerates pleural fluid absorption in mice hydrothoraces

This study assessed the effect of corticosteroid treatment in the clearance of hydrothoraces in mice. Twentyfour C57BL/6 mice were divided into four groups and were injected intrapleurally with 500 mu L sterilized PBS-BSA 1% to create isosmotic hydrothoraces. Two groups served as control and two groups were treated with dexamethasone. The control groups received intraperitoneally PBS, while the corticosteroid treatment groups received dexamethasone (1 mg/kg), both 5 min after the induction of hydrothorax. Control and treated animals were sacrificed 2 and 4 h after the induction of hydrothorax, and pleural fluid volume was measured. The pleural fluid volume 2 and 4 h after the induction of hydrothoraces was significantly lower in the dexamethasone-treated group compared to the untreated group. The rate of pleural fluid absorption 2 and 4 h after the induction of hydrothoraces was significantly higher in the dexamethasone-treated groups. The present study demonstrated that dexamethasone accelerates pleural fluid absorption in induced isosmotic hydrothoraces in mice. This newly reported property of dexamethasone may partly account for the clinical observation of faster resolution of pleural effusions when corticosteroids are administered in patients with pleural effusions of certain etiologies