ABSTRACT
Objective To evaluate the protective effects and mechanism of levocarnitine preconditioning (LCN) on myocardial is-chemia-reperfusion injury in patients undergoing cardiopulmonary bypass .Methods 60 cases of ASA Ⅱ or Ⅲ degree and NYHAⅡ or Ⅲ degree patients who aged 25 ~ 57 years old ,undergoing cardiopulmonary bypass with elective cardiac valve replacement were randomly divided into 2 groups (n = 30 each) :group C (treated with 0 .9% sodium chloride) and group L (treated with LCN) .Group L was infused levocarnitine 50 mg/kg per 1 day at the beginning of 7 days before operation ,group C was given the same amount of 0 .9% sodium chloride .Blood samples were taken from central vein at 5 min after the induction the level of anesthe-sia (T0 ,baseline) ,5 min before aortic cross-clamping (T1) ,30 min after release of the aortic cross-clamp (T2) and at 6 (T3) ,12 (T4) and 24 h (T5) after operation for determination .The level of plasma cardiac troponin I (cTnI) ,creatine kinase-MB (CK-MB) and tumor necrosis factor-α (TNF-α) .Myocardial specimens were obtained from right auricle before aortic cross-clamping and after release of aortic cross-clamp to observe the pathologic changes ,the protein expression of p38 MAPK and phosphorylational-p38 MAPK that analyzed by western blotting .Cardiac index (CI) and left ventricular ejection fraction (LVEF) were measured at 1st day before operation and 7th day after operation by using heart color ultrasonography .Results The levels of cTnI ,CK-MB and TNF-α were significantly lower at all time points in group L than in group C (P< 0 .05) .Myocardial mitochondrion impairment was lighter ,the expression of p38 MAPK and phosphorylational-p38 MAPK were significantly attenuated in group L than in group C (P< 0 .05) .CI and LVEF were significantly higher at 7th day after operation in group L than in group C(P< 0 .05) .Conclusion Le-vocarnitine preconditioning can attenuate myocardial ischemia-reperfusion injury and recover cardiac function in patients undergoing cardiopulmonary bypass ,the mechanism may be related to keep the integrity of the mitochondrial membrane and space structures , inhibit the expression of p38 MAPK and phosphorylational-p38 MAPK and decrease the inflammatory response .