Objective To evaluate the effects of ulinastatin postconditioning and combination of ulinastatin preconditioning and postconditioning on myocardial apoptosis in patients undergoing cardiac valve replacement with cardiopulmonary bypass (CPB).Methods Eighty NYHA class Ⅱ or Ⅲ patients of both sexes,aged 21-59,scheduled for cardiac valve replacement with CPB,were randomly divided into 4 groups ( n =20 each):normal saline control group ( group C ),ulinastatin preconditioning group ( group U1 ),ulinastatin postconditioning group (group U2 ) and ulinastatin preconditioning plus postconditioning group(group U3 ).In group U1,uinastatin 20 000U/kg was infused via central vein at 500-1000 U·kg-1 ·min-1 from after tracheal intubation until 10 min before ascending aortic cross-clamping.In group U2,ulinastatin 10 000 U/kg was perfused via aortic root at 4000-5000 U· kg-1 · min-1 at 5-7 min before aortic unclamping.In group U3,ulinastatin preconditioning and postconditioning were performed as described in groups U1 and U2.In group C same volume normal saline was infused instead of ulinastatin.Blood samples were taken from radial artery at 10 min before ascending aortic cross-clamping,40 min after ascending aortic cross-clamping,45 min after aortic unclamping and the end of operation for determination of plasma concentrations of TNF-α and soluble tumor necrosis factor receptor 1 (sTNF-R1).Myocardial tissues were obtained from right atrial appendage at 45 min after aortic unclamping for determination the expression of TNF-d,Bcl-2,Bax and caspase-3 and apoptosis.The Bcl-2/Bax ratio and apoptotic index were calculated.Results Plasma concentrations of TNF-α and sTNF-R1 and the expression of TNF-α,Bax,caspase-3 and apoptotic index were lower,the expression of Bcl-2 and Bcl-2/Bax ratio were higher in groups U1,U2 and U3 thah group C and in group U3 than groups U1,U2 ( P ＜ 0.05 ).Conclusion Ulinastatin postconditioning can inhibit myocardial apoptosis in patients undergoing cardiac valve replacement with CPB,and efficacy of combination of ulinastatin preconditioning and postconditioning is stronger than that of ulinastatin postconditioning.The mechanism is involved in balancing the expression of Bax and Bcl-2 and down-regulating the expression of TNF-α and its receptor.