The Experimental And Clinical Study On Myocardial Protective Effects Of L-carnitine During Ischemia-Reperfusion

Background and Objective: Myocardial metabolism function disturbance (ischemic and hppoxia) and ischemical reperfusion injury are cardial change of pathologic physiology during the intracardiac operation underdirect vision with cardiopulmonary bypass (CPB),is also the reason of low cardiac output syndrome and vicious cardiac rhythy aberration after operation,thereby,People would explore a favourable method of myocardial protection. To investigate the protective effects of L-carnitine on myocardium during ischemia reperfusion, and explore its possible mechanism, thereby providing rational clinical application.Methods:1,Using rabbit ischemia-reperfusion injury model , twenty-four healthy rabbits of both sexes were randomly divided into there groups of A,B and C .Group A(pseudo-operating group): Group B (operative control group): Group C ( therapeutic group).The index of cardiac hemodynamics of rabbits were respectively recorded with LMS-2B system . Serum creatine phosphokinase(CPK), superoxide dismutase(SOD) activities and malondialdehyde (MDA) concentrations were also measured in each group. Ultrastructural change of cardiac muscle with transmission electron microscope after myocardial reperfusion was examined .Apoptotic index and apoptosis percentage were detected apoptosic of myocardial cell. 2,40 cases undergoing heart valve replacement with cardiopulmonary bypass (CPB),were randomly divided into two groups : L-CN group(n=20),control group(n=20). L-CN group received L-carnitine injection(150mg/kg)in venous blood reservoir of cardiopulmonary bypass unit at 15 min before breaking aorta ,Control group did not receive L-carnitine.Hemodynamic parameters such as HR,MAP,PWAP,CI,SVI and LVSWI were recorded before CPB,2h,8h and 24h after breaking arota by Swan-Gans catheter .Blood samples were taken from central vein.to.determine.phosphokinase(CK-MB).troponinI(cTnI).myoglobin(MYO).malondialde -hyde(MDA).anddsuperoxidedismutase(SOD)activities.at.different.time.The.dosage.of.dop-amine.used.and.the.postoperation.cardiac.auto-rebeating.rate.were.recorded.Ultrastructur-al change of cardiac muscle after myocardial reperfusion was examined .Results: 1,Rabbit ischemia-reperfusion injury model showing. Compared with group B, left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure(LVEDP), and±dp/dtmax were better restored(P<0.05) ,The activity of CPK in the blood plasma and the level of MDA were lower in the group C than those of group B(P<0.01or p<0.05),while the activity of SOD was higher(P<0.01). The ultrastructual damages in L-CN group were milder than in control group. Apoptotic index and apoptosis percentage in L-CN group were lesser than in control group. 2,With regard to heart valve replacement operation, The lever of CI,SVI,LVSWI in L-CN group were significant higher than those in control group after aorta breaking (P<0.05);The levers of cTn I.,MYO,CK-MB and MDA in L-CN group increased less than control group(p<0.01 or P<0.05).But the lever of SOD in L-CN group was higher than control group(P<0.05); The postoperative cardiac auto-rebeating rate in the L-CN group significantly higher than in the control group(P<0.05),Dopamine used after operation was significantly less than in the control group(p<0.05);The ultrastructual damages with transmission electron microscope in L-CN group were milder than in control group.Conclusion:1,Myocardial ischemia-reperfusion can step down the revival of myocardial function.step up myocardium creatase and marker.detriment myocardium mitochondria.2,Cell morphology,Apoptotic index and apoptosis percentage confirm that exist apoptosic after ischemia-reperfusion 3,L-carnitine exerted obvious protective effects on myocardium during ischemia-reperfusion. L-carnitine can accelerate the revival of myocardial function during ischemia-reperfusion, reduce the myocardial infarct size, decrease myocardium creatase and marker, diminish oxyradical and peroxidation, reduce the dosage of vasoactive agent after operation. 4,L-carnitine can lessen the change of myocardium mitochondria ultrastructure during ischemia reperfusion, improve energy metabolism of ischemic myocardium,promote the revival of myocardial function.