【作者】 姚磊；

【导师】 胡申江；

【作者基本信息】 浙江大学 ， 内科学， 2009， 博士

【摘要】 研究背景：以往研究表明，他汀类药物（statins），3′羟基-3′甲基戊二酰辅酶A（3-hydroxy-3-methylglutaryl coenzyme，HMG-COA）还原酶抑制剂，具有多种非调脂作用，能使罹患不同类型心脏疾病的患者受益。近几年，不断地有临床试验和基础研究证据表明，不同种类他汀类药物的使用能有助于心力衰竭患者心功能的提高。细胞内钙稳态对心脏功能非常重要，心肌细胞内钙调节蛋白的异常在心力衰竭发生和发展中起到不可忽视的作用。然而，目前尚不清楚他汀类药物改善心脏功能是否与钙调节蛋白的变化有关。目的：本课题研究atorvastatin对自发性高血压大鼠（spontaneously hypertensive rat，SHR）左心功能的影响，主要关注药物对心肌组织钙调节蛋白的作用，包括肌浆网Ca²⁺-ATP酶SERCA(sarcoplasmic reticulum Ca²⁺-adenosine triphosphatase)，磷酸受纳蛋白PLB（phospholamban）以及磷酸化PLB（phosphorylated PLB）。我们将首次在体研究他汀类药物可否通过影响心肌钙调节蛋白从而促进自发性高血压大鼠左心室功能改善，以阐明对钙调节蛋白的影响是他汀类药物改善左心室功能的可能机制之一。方法：8周龄健康雄性SHR以及同周龄雄性Wistar-Kyoto（WKY）大鼠分组后分别予以1 ml蒸馏水，atorvastatin（50 mg/kg／day），amlodipine（2 mg／kg／day），或两种药物共用，混合于1 ml蒸馏水中灌胃，每日一次共十周。Amlodipine在此作为血压控制对照药物使用。期间每周测尾动脉收缩压（SBP），每二周行超声心动图检查，最后以有创血流动力学方法测平均动脉压（MAP）和收缩期和舒张期左室内压最大变化速率（±dp／dt max）。抽取动脉血测血脂水平；以病理学方法检测心肌细胞横径（TDM）和胶原容积分数（CVF）；用Western blot检测心肌组织中SERCA，PLB和磷酸化PLB蛋白水平的表达；测定心肌肌浆网SERCA活性；测定心肌组织羟脯氨酸含量；ELISA法检测心肌组织内炎症因子IL-6，IL-10和TNF-α含量。结果：8～18周龄SHR血压逐渐增高，伴有左心室／体重比增加，TDM增大，以及CVF和羟脯氨酸含量增高，这提示SHR大鼠存在明显左心室肥大，心室发生重构。此外，SHR心肌组织内炎症因子水平异常，IL-6和TNF-α浓度增高，IL-10浓度降低。Atorvastatin和amlodipine两药均使SHR血压下降，使其左心室重构指标和炎症因子水平有所改善。与WKY相比，SHR左心室收缩和舒张功能逐渐衰退，心肌组织内SERCA和磷酸化PLB蛋白水平表达减少，SERCA活性亦降低。我们发现使用atorvastatin后SHR左心室功能障碍得到有效控制，并且钙调节蛋白亦向着有利于心功能的方向变化，SERCA和磷酸化PLB表达有所上调，SERCA活性有所增加。结论：我们的研究表明，SHR左心室功能障碍的改善很难以atorvastatin和amlodipine在控制血压，改善左心室重构和炎症因子指标等方面的作用来说明。钙调节蛋白的变化可能在该鼠龄段SHR左心室障碍中起了较大作用，atorvastatin对钙调节蛋白的作用是其改善SHR左心室功能的可能机制之一。更多还原

【Abstract】 Background:Previous studies have demonstrated that statins,the inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase,have many effects beyond lipid-lowering,which make them of potential benefit in patients with various heart diseases.Recently,statins were shown to improve cardiac function in clinical and experimental studies,andthis protective effect is being confirmed by growing evidence.Also,intracellular Ca²⁺homeostasis is one of the critical factors responsible for efficient myocardial function,and abnormalities of Ca²⁺-regulating proteins in myocardium are closely involved in thepathogenesis of cardiac dysfunction.However,it is still unclear whether the beneficialeffect of statins on cardiac function is associated with alterations of Ca²⁺-regulatingproteins.Objective:In this study,we investigated the effect of atorvastatin on cardiac function inspontaneously hypertensive rats（SHRs）,focusing in particular on its impact on theexpression of myocardium Ca²⁺-regulating proteins:sarcoplasmic reticulum Ca²⁺-adenosine triphosphatase（SERCA）,phospholamban（PLB）and its phosphorylated form（phosphorylated PLB）.We tried to provide novel in vivo evidence for the potentialmechanism that statin might improve cardiac dysfunction in SHRs via affecting thebehaviors of myocardium Ca²⁺-regulating proteins.Methods:8-week-old male SHRs and Wistar Kyoto rats（WKYs）were given（by gavage for10 weeks）either 1 ml distilled water,atorvastatin（50 mg/kg/day）,amlodipine（2mg/kg/day）,or both,mixed with 1 ml distilled water.Amlodipine here was used as adrug control for blood pressure.Systolic blood pressure（SBP）was measured weekly bythe tail-cuff method.Echocardiographic measurement was performed biweekly duringthe experiment.Mean arterial pressure（MAP）and the positive and negative firstderivatives of LV pressure（±dp/dt max）were measured by hemodynamic studies.Blood lipid levels were then detected.Pathologic studies was used for evaluatingtransdiameter of cardiomyocyte（TDM）and collagen volume fraction（CVF）.Theexpression of SERCA,PLB and phosphorylated PLB protein level were detected byWestern blot analysis.IL-6,IL-10 and TNF-αlevels were quantified,as well as SERCAactivity and hydroxyproline content.Result:SBP of SHRs increase gradually at the age of 8～18 week,accompanied withhigher LVW/BW ratio,larger size of TDM,increased myocardium fibrotic infiltrationand hydroxyproline content,which mean cardiac hypertrophy.Also,SHRs haveabnormal inflammatory cytokine concentrations,with higher IL-6 and TNF-αlevels andlower IL-10 level.Both atorvastatin and amlodipine reduce systolic blood pressure,improve LV remodeling and myocardium inflammatory cytokine markers in SHRs.Inaddition,compared to WKYs,SHRs show decreases in gene expression of SERCA andphosphorylated PLB,and reduction in SERCA activity in left ventricular myocardium, as well as gradually reduced cardiac systolic and diastolic function.Furthermore,weshowed that atorvastatin preserved cardiac dysfunction in SHRs,accompanied bypositive alterations in calcium regulatory proteins,with up-regulation in expression ofSERCA and phosphorylated PLB,and with improvement of SERCA activity.Conclusions:It can not conclude from our data that the improvement of left ventricular functionin SHRs is due either to the beneficial effects of atorvastatin and amlodipine oninflammatory markers,or reduction in blood pressure,or their effects on remodeling.Alterations in Ca2+-regulating proteins may contribute to the cardiac dysfunction inSHRs,and the HMG-CoA reductase inhibitor atorvastatin modulate the proteinexpression and increase the activity of SERCA,which effectively preserve leftventricular function and may be one of the mechanisms of statins’ beneficial effects oncardiac dysfunction in hypertensive rats.更多还原