Objective:To analyze the levels of plasma Apelin-36,nitric oxide (NO)and tumor necrosis factor-alpha (TNF-α) during cardiopulmonary bypass (CPB)in patients with cardiac surgery.Methods:Seventeen patients undergoing elective cardiac procedures with cardiopulmonary bypass were studied.The levels of arterial and venous plasma Apelin-36,NO and TNF-αwere measured by enzyme-linked immunosorbent assay at the following time points:before initiation of operation (T0),imme-diately after aortic declamping (T1),10 minutes after aortic declamping (T2)and the end of CPB (T3).Results:Compared with T0,Apelin-36 levels in arterial plasma elevated at three time points of T1,T2 and T3 (P <0.01 or P <0.05)and in ve-nous plasma elevated at two points of T1 and T2(P <0.01).The arterial plasma NO levels elevated at the time point of T1 and the venous NO levels elevated at the time point of T3(P <0.01 or P <0.05).The arterial plasma TNF-αlevels elevated at two time points of T1 and T3(P <0.01),and elevated in venous plasma at the time point of T3(P <0.01).Conclusions:CPB can increase the levels of plasma Apelin-36,NO and TNF-α.