Effects of cardiopulmonary bypass on expression of tight junction protein occludin in rat lung tissues

Objective To investigate the effects of cardiopulmonary bypass (CPB) on the expression of tight junction protein occludin in rat lung tissues.Methods Twenty adult male Sprague-Dawley rats were randomly divided into 2 groups (n=10 each): sham operation group (group S) and CPBgroup.The rats underwent 1 h of CPB and were observed 2 h later in group CPB.The lung water content,neutrophil percentage and protein concentration in bronchoalveolar lavage fluid (BALF) were measured.The expression of occludin in lung tissues was detected by immunohistochemistry and Western-blot analysis.The ultrastructure of alveolar epithelial barrier was observed with transmission electron microscope.Results Compared with group S,the lung water content,protein concentration in BALF and neutrophil percentage were significantly increased (P ＜ 0.05),the expression of occludin in lung tissues was significantly down-regulated (P ＜ 0.05) and the damage to alveolar epithelial barrier was aggravated in group CPB.Conclusion The expression of occludin in lung tissues is down-regulated and the damage to alveolar epithelial barrier is induced after CPB,which may be one of the important factors in acute lung injury induced by CPB. Key words: Extracorporeal circulation; Respiratory distress syndrome,adult; Tight junctions