Effects of modified ultrafiltration on expression of aquaporin 1 in cardiopulmonary bypass-induced lung injury in dogs

Abstract

Objective To evaluate the effects of modified ultrafiltration on the expression of aquaporin 1 (AQP1) in cardiopulmonary bypass (CPB)-induced lung injury in dogs.Methods Eighteen healthy adult dogs of either sex,weighing 15-20 kg,were randomly divided into 3 groups (n =6 each):control group (group C),group CPB and modified ultrafiltration group (group MUF).The dogs were anesthetized with intraperitoneal 2.5％pentobarbital 25 mg/kg.Thoracotomy was performed in all the three groups and in addition lung injury was produced by CPB in CPB and MUF groups.In group MUF,modified ultrafiltration was performed at 10-15 min after termination of CPB.Arterial blood samples were collected before mechanical ventilation (T1),at end of CPB (T2),and at 1 h after termination of CPB (T3) to calculate respiration index (RI) and oxygenation index (OI).The lungs were removed for microscopic examination of pathologic changes in lung tissues under light microscope and for detection of AQP1 mRNA expression by real-time PCR.Results RI and OI were significantly higher and AQP1 mRNA expression was lower at T2 and T3 than at T1 in CPB and MUF groups (P ＜ 0.05).Compared with group C,RI was significantly increased and AQP1 mRNA expression was down-regulated at T2,3 in CPB and MUF groups,and OI at T2.3 in CPB group and at T2 in MUF group was decreased (P ＜ 0.05).Compared with group CBP,RI was significantly decreased,OI was increased and AQP1 mRNA expression was up-regulated at T3 in group MUF (P ＜ 0.05).Conclusion Modified ultrafiltration can reduce CPB-induced lung injury in dogs and upregulation of AQP1 may be involved in the mechanism. Key words: Ultrafiltration ; Cardiopulmonary bypass ; Aquaporin 1