Abstract:

Objective To investigate the expression of aquaporin 1 (AQP1) in myocardial tissues of sheep after cardiopulmonary bypass and its relationship with myocardial edema. Methods Twenty-four healthy adult sheep were randomly divided into normal control group (n=6) and cardiopulmonary bypass group (n=18), and animal samples were obtained at 6 time points (2 h, 6 h, 12 h, 24 h, 48 h and 72 h) after cardiopulmonary bypass in cardiopulmonary group, with 3 sheep at each time point. Real-Time PCR, Western blotting, ELISA and dry/wet method were employed to determine the expression of AQP1 in myocardial tissues of ventricles and severity of myocardial edema at different time points after cardiopulmonary bypass in two groups. Results There existed expression of AQP1 in myocardial tissues of ventricles of sheep in normal control group, and there was no significant difference between myocardial tissues of left ventricles and those of right ventricles (P>0.05). In cardiopulmonary bypass group, there were significant differences in the expression of AQP1 in myocardial tissues among different time points after cardiopulmonary bypass (P<0.05), and the expression tendency of AQP1 mRNA was in line with that of AQP1 protein. The expression of AQP1 mRNA and AQP1 protein in cardiopulmonary bypass group began to decrease after cardiopulmonary bypass, reached the minimum level 6 h after cardiopulmonary bypass, increased from then on, reached the peak level 48 h after cardiopulmonary bypass, and decreased after that time point. There were significant differences in the severity of myocardial edema among different time points after cardiopulmonary bypass (P<0.05). The severity of myocardial edema began to increase after cardiopulmonary bypass, reach the peak level 48 h after cardiopulmonary bypass, and began to decrease after that time point. The relative expression of AQP1 mRNA was positively related to that of AQP1 protein （r=0.971，P<0.05）, and AQP1 protein was positively related to the water content in myocardium （r=0.592，P<0.05）. Conclusion Cardiopulmonary bypass may influence the expression of AQP1 and severity of myocardial edema in sheep, and there is positive relationship between AQP1 protein and myocardial edema.

Key words: cardiopulmonary bypass, cardiac edema, aquaporin-1