Role of aquaporin 1 expression in cardiopulmonary bypass-induced lung injury in dogs

Objective To evaluate the role of aquaporin 1(AQPI)expression in the cartiopulmonary bypass(CPB)-induced lung injury in dogs.Methods Twenty-four healthy dogs,weighing 15-20 kg,were randomly divided into 4 group(n =6 each):control group(group C),acetazolamide Ⅰ group(group A Ⅰ),acetazolamide Ⅱ group(group A Ⅱ),and acetazolarnide Ⅲ group(group AⅢ).Lung injury was produced by CPB.The traditional priming solution was infused in group C.Priming solutions containing acetaaolamide 20,40 and 60 mg/kgwere infused in groups A Ⅰ,A Ⅱ and A Ⅲ respectively.Blood samples were collected from the femoral artery before mechanical ventilation,at the end of CPB and at 1 h after end of CPB(T1-3)for arterial blood gas analysis.Respiration index(RI)and oxygenation index(OI)were calculated.The lung specimens were oblained for determination of AQPI mRNA and protein expression(by RT-PCR and Western blot)and for microscopic examination.The pathological changes of the lung were scored.Results Compared with group C,P(A-a)O2,RI and the pathological score were significantly increased at T2.3,OI was significantly decreased at T2.3,and AQP1 protein expression was down-regulated at T2.3 in groups A Ⅰ,A Ⅱ and AⅢ,and AQP1 mRNA expression was down-regulated at T2.3 in groups AⅡ and AⅢ(P＜0.05).Compared with group A Ⅰ,P(A-a)O2,RI and the pathological score were significantly increased at T2.3,OI was significantly decreased at T2.3,and AQP1 protein expression was down-regulated at T2.3 in groups A Ⅱ and AⅢ,and AQP1 mRNA expression was down-regulated at T2.3 ingroup A Ⅲ(P ＜ 0.05).Compared with group A Ⅱ,RI and the pathological score were significantly increased at T2.3,and AQP1 protein expression was down-regulated at T2.3 in group A Ⅲ(P ＜ 0.05).Conclutsion Down-regulation of AQPI expression is involved in the CPB-induced lung injury in dogs. Key words: Aquaporin 1; Extracorporeal circulation; Respiratory distress syndrome, adult