Effects of dexamethasone on absorption of lung edema in rabbits with seawater drowning-induced acute lung injury

Objective To investigate the effects of dexamethasone on absorption of lung edema in rabbits with seawater drowning-induced acute lung injury.Methods Seawater(4 ml/kg body weight)was instilled into the lower trachea of ventilated and anesthetized rabbits.These rabbits were assigned randomly to receive intravenous injection of 1 mg/ kg body weight of dexamethasone(dexamethasone group,DG)or 2 ml of normal saline(control group,CG).Lung edema was measured by extravascular lung water index(EVLWI)using a gravimetric method.Three hours after treatment, epithelial Na~+ channel subunit-α(α-ENaC)mRNA and Na~+/K~+-adenosine triphosphatase subunit-αl(NKA-αl) protein abundances in lung tissues were respectively measured by reverse transcriptase-polymerase chain reaction and Western blotting,and NKA activity was measured by monitoring the release of inorganic phosphate(Pi)from adenosine triphosphate(ATP).Results The DG's EVLWI was significantly lower than the CG's[(0.508±0.089)vs.(0.648±0.102),P＜0.05)],but the DG's NKA activity,α-ENaC mRNA and NKA-αl protein abundances were significantly higher than the CG's,correspondingly(P＜0.05).Conclusions With up-regulation of the NKA activity and expressions ofα-ENaC and NKA-αl,dexamethasone treatment could promote the absorption of lung edema in rabbits with seawater drowing-induced acute lung injury.