儿茶酚抑素对心肌梗死大鼠心室肌细胞钙转运及室性心律失常的影响

Effects of catestatin on calcium handling abnormalities and ventricular arrhythmia after myocardial infarction in rats

目的:探讨儿茶酚抑素(CST)对心肌梗死(MI)大鼠心室肌细胞钙转运及室性心律失常(VA)的影响。方法:雄性SD大鼠85只,随机分为假手术(sham)组(n=20)和手术组(n=65)。手术组动物结扎左冠状动脉前降支制备大鼠MI模型,假手术组只剪开心包并不结扎冠状动脉。将术后存活1周的手术组大鼠随机分为梗死对照组(MI组)和CST干预组(CST组)。CST组给予CST(30 mg·kg^-1·d^-1)连续4周腹腔注射,MI组和假手术组则注射等量生理盐水。急性分离大鼠心室细胞,钙荧光染料Fura-2 AM孵育后行心肌细胞钙成像实验。在Langendorff灌流条件下行离体电生理研究,评价各组动作电位时程(APD)电交替及VA易感性。Western blot法检测心室钙/钙调素依赖性蛋白激酶II(CaMKII)、磷酸化CaMKII(p-CaMKII)、ryanodine受体2(RyR2)及磷酸化RyR2(p-RyR2)的蛋白水平。结果:与sham组相比,MI组心室p-RyR2和p-CaMKII蛋白水平、心室细胞舒张期Ca ^2+水平及VA诱发率均显著升高,而心室细胞Ca 2+瞬变(CaT)幅度、CaT交替诱发阈值及APD电交替诱发阈值均显著降低(P<0.01);与MI组相比,CST组心室p-RyR2和p-CaMKII蛋白水平、心室细胞舒张期Ca ^2+水平及VA诱发率均显著降低,而心室细胞CaT幅度、CaT交替诱发阈值及APD电交替诱发阈值均显著增加(P<0.01)。心室RyR2及CaMKII的表达量在3组间差异无统计学显著性(P>0.05)。结论:CST可降低MI大鼠VA易感性,其机制可能与CST修复心室细胞Ca^ 2+转运有关。

AIM:To determine the effects of catestatin(CST)on calcium handling abnormalities and ventri-cular arrhythmia(VA)after myocardial infarction(MI)in rats.METHODS:The adult male SD rats(n=85)were randomly divided into sham group(n=20)and operation group(n=65).MI was induced by ligation of the left anterior descending coronary artery in operation group.The rats in sham group underwent pericardiotomy but without ligating the artery.The rats survived for 1 week after operation were randomly assigned to MI group and CST group.The rats in CST group was treated with CST(30 mg·kg^-1·d^-1,intraperitoneal administration)for 4 weeks,while saline was applied to the rats in sham group and MI group.The calcium imaging study was performed by loading isolated ventricular cardiomyocytes with Fura-2 AM.In the whole Langendorff-perfused hearts,the programmed electrical stimulation was used to induce action potential duration(APD)alternans and VA.The protein levels of ryanodine receptor 2(RyR2),phosphorylated RyR2(p-RyR2),calcium/calmodulin-dependent protein kinase II(CaMKII)and phosphorylated CaMKII(p-CAMKII)were determined by Western blot.RESULTS:Compared with sham group,the protein levels of p-RyR2 and p-CaMKII,the diastolic intracellular Ca ^2+concentrations and the inducibility of VA were significantly increased,whereas the thresholds of Ca 2+transient(CaT)and APD alternans and the CaT amplitude were markedly decreased in MI group(P<0.01).Compared with MI group,the protein levels of p-RyR2 and p-CaMKII,the diastolic intracellular Ca ^2+concentration and the inducibility of VA were significantly decreased,while the thresholds of CaT and APD alternans and the CaT amplitude were markedly increased in CST group(P<0.01).No significant difference of the protein expression of RyR2 and CaMKII among the 3 groups was observed(P>0.05).CONCLUSION:CST reduces the susceptibility to VA after MI via preventing calcium handling abnormalities.