Abstract: Background　Dilated cardiomyopathy is a major cause of heart failure（HF）. Effective components of Yixintai（ECYXT）have proven to be very effective against HF，but the mechanism of action is not completely clear. Objective　To explore the effects of the ECYXT on the protein and mRNA expression of CaN and SERCA2a in myocardial tissue of a rabbit model of HF induced by dilated cardiomyopathy. Methods　The rabbit model of HF was established by injecting adriamycin into the marginal ear vein and giving propylthiouracil by gavage in January 2018. The rabbits successfully modeled were divided into HF model group〔n=17，single intragastric dose of 0.9% saline solution（10 ml/kg） per day〕，groups of low dose ECYXT 〔n=17，single intragastric dose of ECYXT solution（10 ml/kg） with a concentration of 2.1 g/kg per day〕，medium dose ECYXT〔n=17，single intragastric dose of ECYXT solution（10 ml/kg） with a concentration of 4.2 g/kg per day〕，high dose ECYXT〔n=17，single intragastric dose of ECYXT solution（10 ml/kg） with a concentration of 8.4 g/kg per day〕，and losartan potassium group〔n=16，single intragastric dose of losartan potassium suspension（10 ml/kg） with a concentration of 2.75 mg/kg〕. And other 20 rabbits were selected for comparison〔control group，single intragastric dose of 0.9% saline solution（10 ml/kg）per day〕. The intervention for all groups lasted for 4 weeks.When the experiment ended，serum atrial natriuretic peptide（ANP），brain natriuretic peptide（BNP），left ventricular ejection fraction（LVEF），left ventricular short-axis shortening（LVFS），and E/A ratio of the rabbits were measured，then the rabbits were sacrificed and cardiac muscles were obtained to observe the myocardial tissue morphology，and to measure the concentration of ［Ca2+］i in myocardial cells，the protein and mRNA expression of CaN and SERCA2a in myocardial tissue. Results　HF model group showed edema and necrosis of cardiomyocytes，with shrinkage of nuclei，widening of intercellular substance，and a small amount of inflammatory cells exuded，and demonstrated disordered arrangement of myocardial fibers，with some broken. Compared with HF model group，the injury of myocardial cells in each dose group of ECYXT and losartan potassium group was alleviated in varying degrees，especially in medium and high dose groups of ECYXT，and losartan potassium group. Compared with the control group，HF model group demonstrated increased levels of serum ANP and BNP，decreased LVEF，LVFS，and E/A ratio，elevated concentration of ［Ca2+］i
in myocardial cells and protein and mRNA expression levels of CaN in myocardial tissue，as well as reduced protein and mRNA expression levels of SERCA2a in myocardial tissue（P<0.01）. Compared with HF model group，three ECYXT groups and losartan potassium group had decreased serum ANP and BNP，increased LVEF，LVFS and E/A ratio，reduced concentration of ［Ca2+］i in myocardial cells，and protein and mRNA expression levels of CaN in myocardial tissue，as well as increased protein and mRNA expression levels of SERCA2a in myocardial tissue（P<0.01）. Compared with the low dose ECYXT group，medium and high dose ECYXT groups and losartan potassium group presented decreased levels of serum ANP and BNP，increased LVEF，LVFS and E/A ratio，reduced concentration of ［Ca2+］i in myocardial cells，and protein and mRNA expression levels of CaN in myocardial tissue，as well as increased protein and mRNA expression levels of SERCA2a in myocardial tissue（P<0.01）. The above-mentioned indicators in the medium dose ECYXT group were similar to those in high dose ECYXT group and losartan potassium group（P>0.05） except that the protein and mRNA expression levels of SERCA2a in myocardial tissue were increased in the latter two groups（P<0.01）. There were no significant differences in the above-mentioned indicators between high dose ECYXT group and losartan potassium group（P>0.05）. Conclusion　ECYXT could improve the protein and mRNA expression of SERCA2a in myocardial tissue，decrease the concentration of ［Ca2+］i in myocardial cells，inhibit the protein and mRNA expression of CaN in myocardial tissue，indicating that ECYXT improve heart function and HF induced by dilated cardiomyopathy in the rabbit model.

Key words: Heart failure；Cardiomyopathy, dilated；Cardiovascular agents（TCD）；Yixintai；Effective components；CaN；SERCA2a；Models, animal

摘要： 背景　扩张型心肌病是心力衰竭的主要病因之一，益心泰具有较好的抗心力衰竭作用，但具体作用机制尚不完全明确。目的　探讨益心泰有效组分（ECYXT）对扩张型心肌病心力衰竭兔心肌组织钙调神经磷酸酶（CaN）、肌浆网钙泵（SERCA2a）mRNA及蛋白表达水平的影响。方法　2018年1月，采用阿霉素耳缘静脉注射+丙基硫氧嘧啶混悬液灌胃复制兔心力衰竭模型。将造模成功的模型兔分为心力衰竭模型组（17只）、ECYXT低剂量组（17只）、ECYXT中剂量组（17只）、ECYXT高剂量组（17只）和氯沙坦钾组（16只），另设正常对照组（20只）。ECYXT各剂量组分别予以浓度2.1 g/kg、4.2 g/kg、8.4 g/kg的ECYXT进行灌胃处理，氯沙坦钾组予以2.75 mg/kg氯沙坦钾悬液进行灌胃处理，心力衰竭模型组和正常对照组予以等量的0.9%氯化钠溶液；6组灌胃量均为每次10 ml/kg，1次/d，连续4周。比较各组兔心肌组织形态学，血清心钠肽（ANP）、脑钠肽（BNP）水平，左心室射血分数（LVEF）、左心室短轴缩短率（LVFS）和E峰与A峰的比值（E/A比值）等心功能情况，心肌细胞［Ca2+］i浓度，心肌组织CaN、SERCA2a mRNA及蛋白表达水平。结果　心力衰竭模型组心肌细胞出现水肿、坏死，胞核皱缩，间质变宽，少许炎细胞浸润，心肌纤维排列紊乱，部分断裂。ECYXT各剂量组和氯沙坦钾组心肌细胞损伤程度均较心力衰竭模型组有所减轻，以ECYXT中剂量组、ECYXT高剂量组、氯沙坦钾组较为明显。与正常对照组比较，心力衰竭模型组血清ANP、BNP水平升高（P<0.01），LVEF、LVFS、E/A比值降低（P<0.01），心肌细胞［Ca2+］i浓度及心肌组织CaN mRNA、蛋白表达水平升高（P<0.01），心肌组织SERCA2a mRNA、蛋白表达水平降低（P<0.01）。与心力衰竭模型组比较，ECYXT各剂量组和氯沙坦钾组血清ANP、BNP水平降低（P<0.01），LVEF、LVFS和E/A比值升高（P<0.01），心肌细胞［Ca2+］i浓度及心肌组织CaN mRNA、蛋白表达水平下降（P<0.01），心肌组织SERCA2a mRNA及蛋白表达水平升高（P<0.01）。与ECYXT低剂量组比较，ECYXT中剂量组、ECYXT高剂量组和氯沙坦钾组血清ANP、BNP水平降低（P<0.01），LVEF、LVFS和E/A比值升高（P<0.01），心肌细胞［Ca2+］i浓度及心肌组织CaN mRNA、蛋白表达水平下降（P<0.01），心肌组织SERCA2a mRNA及蛋白表达水平升高（P<0.01）。ECYXT高剂量组和氯沙坦钾组与ECYXT中剂量组比较，心肌组织SERCA2a mRNA及蛋白表达水平升高（P<0.01），其余指标比较，差异均无统计学意义（P>0.05）。ECYXT高剂量组与氯沙坦钾组比较，以上各指标差异 均无统计学意义（P>0.05）。结论　ECYXT可提高心肌组织SERCA2a mRNA及蛋白表达水平，降低心肌细胞［Ca2+］i浓度，抑制心肌组织CaN mRNA及蛋白表达，提高心功能，改善心力衰竭。

关键词: 心力衰竭；心肌病, 扩张型；心血管药物（中药）；益心泰；有效组分；钙调神经磷酸酶；肌浆网钙泵；模型, 动物