β肾上腺素能受体在左室机械辅助减负荷模型中的表达

目的 研究β肾上腺素能受体在左室机械辅助减负荷模型中的表达及其意义,探讨左室减负荷后心肌分子水平的变化.方法 选用Lewis大鼠,结扎冠状动脉左前降支(LAD)诱导心力衰竭(心衰);4周后,心脏移植组将心衰后的心脏及右肺移植到受体大鼠的腹部(通过供体的升主动脉与受体的降主动脉吻合);移植2周后,评价全心重量、左室重量、心肌细胞直径及心肌纤维化程度,采用实时定量聚合酶链反应(PCR)检测β肾上腺素能受体mRNA的表达.以7只正常Lewis大鼠为对照.结果 心衰后增大的心脏、左室重量、左室心肌细胞直径在移植后趋于正常.心衰组左室β1、β2肾上腺素能受体mRNA表达较正常组明显降低(0.09±0.03比0.18±0.04,0.07±0.06比0.12±0.02,均P<0.05);移植组β2肾上腺素能受体mRNA 表达(0.11±0.05)接近正常组(P>0.05),而β1肾上腺素能受体mRNA表达(0.08±0.06)仍低于正常组(P<0.05).结论 左室减负荷后,心肌逆向重构的过程伴随着心肌细胞分子水平改变,如β肾上腺素能受体表达的改变,可能与左室机械辅助后心脏功能的恢复有关.

Abstract：

Objective To study the expression and significance of β adrenergic receptors mRNA in a model of left ventricular mechanical unloading,and explore the change in cardiomyocyte in molecular level after left ventricular unloading.Methods Heart failure was reproduced in Lewis rats by ligating left anterior descending(LAD)artery.After 4 weeks,the failing hearts and right lungs were heterotopically transplanted into the abdomen of the recipients by anatomizing their ascending aorta to the recipients'descending aorta in the heart transplantation group.Two weeks after transplantation,heart weight,left ventricular weight,myocyte diameter and myocardial fibrosis were determined,and β adrenergics receptors mRNA expression was essayed by real-time polymerase chain reaction(PCR).Seven normal Lewis rats served as control.Results The weight of the enlarged heart,left ventricular weight and myocyte diameter of the failing hearts were decreased to normal after transplantation.The levels of β1-and β 2-adrenergic receptors mRNA expression were significantly lowered in heart failure group compared with that of normal group(0.09±0.03vs.0.18±0.04,0.07±0.06 vs.0.12±0.02,both P<0.05).The level of β2-adrenergic receptor mRNA expression in heart transplantation group(0.11±0.05)rose to normal(P>0.05),but β1-adrenergic receptor mRNA expression(0.08±0.06)was lower in heart transplantation group than that in normal group (P<0.05).Conclusion Myocardium reverse remodeling after left ventricular unloading is accompanied by the change in cardiomyocyte in molecular level,such as the change in β adrenergic receptors,which may involve in the improvement of heart function after being supported by left ventricular assist device.