Effect Of Trimetazidine On Ischemia/Reperfusion-mediated Myocyte Apoptosis In New Zealand White Rabbits

OBJECTIVE: Myocyte apoptosis resulted from ischemia/reperfusion (I/R) have been demonstrated in animal models as well as in patients with acute myocardial infarction, and oxidative stress have been found to play a critical role in I/R-mediated myocyte apoptosis. Trimetazidine, an antioxidant agent, has been extensively used in coronary artery disease and other cardiovascular disease. Also, it has been shown that trimetazidine may prevent cells from postischemia reperfusion-mediated apoptosis in hepars, kidneys, intestines and retinas. But it's not clear whether trimetazidine may inhibit myocytes from I/R-mediated apoptosis. In present study, we investigated the effect of trimetazidine in I/R-mediated myocyte apoptosis in New Zealand White rabbits.METHODS: Thirty male New Zealand White rabbits were randomly divided into three groups: sham, control and treatment. Each involves ten rabbits. The rabbits were fed daily with ordinary food. Each animal in treated group was additionally fed daily with trimetazidine (vasorel, made in ServierInternational Co. in French, 2mg·kg₁·day₁). Two weeks later, the model of I/R was established. In the sham group, the heart was exposed after the chest had been opened, but coronary artery wasn't ligated. In 150 minutes after the procedure, the animals were killed. In the other two groups, the rabbits were subjected to a thirty-minute coronary occlusion followed by a two-hour reperfusion. Electrocardiogram was recorded before ischemia and postischemia respectively, and ST segment elevation means success in establishment of model. The blood was extracted from right atrium before the animal was killed, and the blood was isolated with hypothermia high speed centrifugation. The serum was kept in hypothermia refrigeration(–70℃). The lesion of myocardium was resected promptly after animal was killed, and was embedded in paraffin wax after fixed with 10% neutral formaldehyde solution and disposed with routine histological methods. The apoptotic myocytes were assessed by terminal deoxynuckeotidyl transferase-mediated dUTP nick end labeling (TUNEL). Also, the total activity of serum superoxide dismuase(T-SOD) were tested by the method of xanthine oxidase, and the contents of serum malondialdehyde(MDA) were checked by colorimetry.RESULTS: As compared with sham group, I/R induced markedly increasing apoptosis of myocytes in control group[(24.58±1.32)% vs (0.43±0.16)%, P<0.001]. T-SOD was significantly depressed(66.40±7.92 vs 89.25±1.36μU/L, P<0.001), and the contents of serum MDA was markedlyincreased(18.52±1.51 vs 5.75±0.95μmol/L,P<0.001).Though the apoptotic index in the treated group[(12.83±1.13)%] is still more than that in sham group(P<0.001), it is significantly fewer than that in control group(P<0.001). Neither T-SOD nor MDA is significant difference between the treated group and the shame group (T-SOD: 88.81±2.81μU/L vs 89.25±1.36μU/L, P>0.05. MDA: 5.49±0.74 vs 5.75±0.95μmol/L, P>0.05) . But compared with the control group, pretreatment with trimetazidine significantly increased T-SOD(88.81±2.81μU/L vs 66.40±7.92, P<0.001) and decreased the concentration of serum DMA(5.49±0.74μmol/L vs 18.52±1.52, P<0.001). In control group, the apoptotic index and serum T-SOD were negatively collated(r=–0.814, P<0.01). But the apoptotic index and the concentration of serum MDA were positively correlated( r=0.859, P<0.01).CONCLUSION: These data suggest that I/R markedly induced myocyte apoptosis and depressed the activity of antioxidase. Free radicals play an important role in I/R-mediated myocyte apoptosis. Pretreatment with trimetazidine may effectively prevent myocyte apoptosis from postischemia reperfusion via antioxidant mechanism.