Effect Of Large Dose Of Ulinastatin On Coagulation-fibrinolysis System During Normothermia Cardiopulmonary Bypass In Rabbits

Background Ulinastatin is a broad-spectrum nonspecific serine protease inhibitor.It decreases systemic inflammatory reaction,which was caused by cardiopulmonary bypass(CPB), reduces the productions of inflammatory mediators.However,it does not have blood protection at present clinical dose,like another broad-spectrum nonspecific serine protease inhibitor aprotinin.Most blood coagulation factors in the waterfall of coagulation have serine in their active sites.Only three factors of them are not serine proteases. Blood protection effect of aprotinin is dose-dependent.When blood concentration of aprotinin is up to 50KIU/ml,it can inhibit plasmin activity.When its concentration reaches 125KIU/ml,it can inhibit the activation of plasminogen.When its level gets to 200—250KIU/ml,it can inhibit not only plasmin,but also kallikrein.It is indicated by experiments in vitro,that the effect of ulinastatin on serine proteases is also dose- dependent.It can inhibit plasmin at a dose of 830 U/ml. Only when its concentration excesses 3000 U/ml,it can inhibit thrombin and kallikrein.The clinical dose of ulinastatin is much lower than that of aprotinin.From the above,it is presumed that large dose of ulinastatin may have blood protection.According to the experimental results in vitro,the large dose of ulinastatin is defined as 10×10~4U/kg.Objective(1) To observe the changes in coagulation-fibrinolysis system and platelet function after CPB;(2) To investigate the effect of large dose of ulinastatin on coagulation-fibrinolysis system and platelet function during CPB by establishing the rabbit model of normothermia cardiopulmonary bypass.Methods A double-blind randomized controlled animal trial is performed.Twenty healthy tamed rabbits(Big white ear) are randomly assigned to control group(group C,n=10) and experiment group(group U,n=10).All the rabbits are male with the age from five to six months and weight from two to three kilograms.A model of normothermia cardiopulmonary bypass is established with rabbits.The rabbits in group U are administered ulinastatin 10×10~4U /kg before CPB,the rabbits in group C are received a same volume of saline at the same time.All rabbits were undergoing extracorporeal circulation for 30min,at a perfusion flow of 180—300ml/min,while their rectal temperature are maintained from 36.5℃to 37.5℃. Hemodynamic parameters are recorded before CPB,at termination of CPB,1 hour,2 hour and 3 hour after CPB.APTT,PT,FIB,D-dimer, blood platelet count,platelet adhesion reaction and platelet membrane glycoprotein GpⅠb,GpⅡb,GpⅢa are determined at the above time point respectively.Results(1) APTT is prolonged after CPB in both group U and C(p＜0.05),but APTTs after CPB in group U are significantly longer than those in group C respectively(p＜0.05).(2) PT is prolonged after CPB in both group U and C(p＜0.05). There is a significant difference in PT between group U and group C at 4h after CPB.The latter is significantly longer than the former (p＜0.05).(3) All levels of FIB in both group U and C are decreased after CPB(p＜0.05),but the levels of FIB after CPB in group U are obviously higher than those in group C respectively(p＜0.05).(4) All concentrations of D-dimer in both group U and C are increased after CPB(p＜0.05),but the concentrations of D-dimer after CPB in group U are significantly lower than those in group C respectively(p＜0.05).(5) The platelet adhesion rates in both group U and C are descended after CPB(p＜0.05),but the platelet adhesion rates after CPB in group U are significantly higher than those in group C respectively(p＜0.05).(6) The platelet counts in both group U and C are decreased significantly after CPB(p＜0.01),but there are no differences between group U and group C after CPB(p＞0.5). (7)The molecular number of GpⅠb,GpⅡb,GpⅢa in both group U and C are reduced after CPB(p＜0.01),but the positive expressions of GpⅠb,GpⅡb,GpⅢa after CPB in group U are significantly higher than those in group C respectively(p＜0.05).Conclusion(1) Over consumption of blood coagulation factors during CPB results in prolonged APTT and PT. Hyperfibrinolysis decreases levels of FIB,increases concentrations of DD,reduces platelet counts,depletes GpⅠb,GpⅡb and GpⅢa,and damages aggregation and adhesion function of the platelet. (2)Administration of large dose of ulinastatin before CPB can reduce the consumption of blood coagulation factors during CPB,promote coagulation after CPB,inhibit excessive activation of fibrinolysis system,reduce breakdown of platelet membrane glycoproteins,and maintain normal function of platelet.It suggests that large dose of ulinastatin may have blood protection.