急性心肌梗死大鼠钙调蛋白的改变及卡维地洛的干预作用

目的：研究急性心肌梗死（AMI）后心力衰竭大鼠心肌钙调蛋白肌质网Ca2+-ATP酶（SERCA）和受磷蛋白（PLB)的变化及卡维地洛对其干预作用。 方法： 选取AMI术后成活的雄性SD大鼠随机分为AMI组、卡维地洛组两组。给药6周后观察血流动力学参数、心室重构指标及钙调蛋白SERCA、PLB的蛋白和mRNA表达。另设正常对照组及假手术组。 结果： AMI组左室舒张末压（LVEDP）、各心室重量均显著大于假手术组，左室内压最大收缩和舒张速率（±dp/dt）显著低于假手术组；SERCA蛋白和mRNA表达显著低于假手术组（P<0.01），PLB蛋白和mRNA表达高于假手术组（P<0.01）。卡维地洛组的LVEDP、心室重量均显著低于AMI组，±dp/dt显著高于AMI组；卡维地洛治疗使SERCA蛋白和mRNA表达明显升高（P<0.05），但未能改变PLB蛋白和mRNA水平(P>0.05）。 结论： 急性心肌梗死后心力衰竭中钙调蛋白SERCA和PLB的变化可能是心肌收缩功能失调的重要机制；卡维地洛能有效地抑制大鼠AMI后心室重构并改善血流动力学，其分子机制可能与钙调蛋白SERCA含量正常化有关。

Changes of calcium handling protein after acute myocardial infarction in rats and effect of carvedilol

AIM: To observe the changes of sarcoplasmic reticulum Ca2+-ATPase (SERCA)， phospholamban (PLB) during heart failure after acute myocardial infarction (AMI) in rats and the effect of carvedilol. METHODS: Rats were randomly assigned to normal control group, sham-operation group, AMI group and carvedilol (CAR) group. 6 weeks later, in vivo hemodynamic, morphometry and SERCA, PLB mRNA and protein expression of myocytes were measured in all animals. RESULTS: In comparison with sham-operation group, LV end diastolic pressure (LVEDP) and weight of ventricles were increased, while maximal rate of rise and fall (±dp/dt) of LV pressure were decreased in AMI group. After treatment with carvedilol, these parameters were all improved. The mRNA and protein expression of SERCA were downregulated (P<0.01). PLB mRNA and protein expression were upregulated (P<0.01) in AMI group relative to sham-operation group. Carvedilol restored the low expression of SERCA mRNA and protein (P<0.05), but was no effect on PLB mRNA and protein expression (P>0.05). CONCLUSIONS: The changes of SERCA and PLB may be the important mechanism of contractile dysfunction in heart failure after AMI. Carvedilol is effective in preventing LV dysfunction after AMI. The molecular mechanism may be related with normalization of SERCA expression.