【作者】 方欣；

【导师】 管思明；

【作者基本信息】 华中科技大学 ， 老年医学， 2009， 博士

【摘要】 目的研究经典的瞬时受体电位通道（TRPC）在纤维化心肌中的表达，为探讨TRPC通道蛋白在心肌纤维化中的作用奠定基础。方法雄性SD大鼠20只，体重180～220g，随机分为两组，每组10只：假手术组（sham-operated group，Sham），分离腹主动脉但不结扎；腹主动脉缩窄组（coarctationof abdominal aorta group，CAA），行腹主动脉缩窄术。术后4周采用颈动脉测压法记录大鼠血压后，处死大鼠切取心脏，HE染色观察心脏结构，并计算心脏与体重比值（心室容积分数）。苦味酸酸性复红法胶原纤维染色（Van-Gieson,VG）测定Ⅰ、Ⅲ型胶原，RT-PCR及Western blot测定心脏组织中TRPC基因及蛋白表达，免疫组织化学方法进一步检测TRPC在心脏组织中的分布与表达。结果CAA组术后4周大鼠血压、左室容积分数及Ⅰ、Ⅲ型胶原容积分数显著高于Sham组（P＜0．01）。CAA组与Sham组比较：TRPC1基因与蛋白表达明显增加，有显著统计学差异（P＜0．01）；TRPC3基因与蛋白表达无明显变化，无统计学差异（P＞0．05）；TRPC6基因与蛋白表达均明显较少，2组无明显差异。TRPC1与心肌Ⅰ、Ⅲ型胶原容积分数呈明显正相关（相关系数r1=0．961，P＜0．01；r2=0．986 P＜0．01）。免疫组织化学染色进一步证实TRPC1蛋白沿细胞膜分布并在纤维化心肌中表达增多。结论纤维化心肌中TRPC1蛋白表达明显增加，可能在腹主动脉缩窄引起的心肌纤维化中发挥重要作用。目的研究血管紧张素Ⅱ（angiotensinⅡ，AngⅡ）对心肌成纤维细胞中TRPC1通道表达及功能的影响，并采用阻断TRPC1通道等药物干预，探讨AngⅡ对心肌成纤维细胞增殖及转化生长因子-β1（transforming growth factor beta,TGF-β1）表达的影响，旨在阐明TRPC1通道蛋白在AngⅡ促心肌纤维化中的作用。方法分离乳鼠心肌成纤维细胞，运用实时定量PCR及Western blot检测不同浓度的AngⅡ(10^-7、10^-6、10^-5mol·L^-1)或高浓度(10^-5mol·L^-1)的AngⅡ在不同时间（0、12和24h）对心肌成纤维细胞TRPC1及TGF-β1基因与蛋白表达的影响；继而，在高AngⅡ状态下(10^-5mol·L^-1)，分别加入以下药物：TRPC1的阻断剂SKF96365、内质网Ca²⁺-ATP抑制剂毒胡萝卜素或L型Ca²⁺通道阻断剂维拉帕米培养心肌成纤维细胞24h，采用MTT、实时定量PCR和Western blot观察心肌成纤维细胞增殖及TGF-β1表达变化；此外，采用激光扫描共聚焦显微镜观察毒胡罗卜素或SKF96365预处理心肌成纤维细胞30min，高浓度AngⅡ(10^-5mol·L^-1)对心肌成纤维细胞胞浆中Ca²⁺的影响。结果AngⅡ呈浓度与时间依赖性升高心肌成纤维细胞中TRPC1基因与蛋白表达。SKF96365及毒胡萝卜素均可明显抑制AngⅡ(10^-5mol·L^-1)刺激24h后诱导的心肌成纤维细胞增殖及TGF-β1表达（P＜0．01）；维拉帕米抑制心肌成纤维细胞增殖（P＜0．01），但TGF-β1表达无明显减少（P＞0．05）。高浓度AngⅡ(10^-5mol·L^-1)显著升高细胞内游离Ca²⁺浓度（P＜0．01）；毒胡萝卜素预处理30min，当胞外液无Ca²⁺时，AngⅡ引起胞内Ca²⁺一过性升高；当胞外存在Ca²⁺时，AngⅡ引起的胞内Ca²⁺持续增加；SKF96365明显抑制AngⅡ升高胞浆Ca²⁺浓度效应。结论：心肌成纤维细胞中，TRPC1表达可随AngⅡ浓度或刺激时间增加而增加;AngⅡ通过促进钙库内Ca²⁺释放，继而激活钙库操纵的钙通道（SOC），致胞外Ca²⁺内流，胞浆内Ca²⁺浓度升高；TRPC1蛋白可能为SOC的分子实体，通过介导胞外Ca²⁺内流，促进AngⅡ刺激的心肌成纤维细胞增殖及TGF-β1表达；SKF96365可阻断TRPC1表达及功能发挥抗纤维化作用。目的研究不同浓度的缬沙坦在高AngⅡ状态下对心肌成纤维细胞TRPC1通道表达的影响。方法分离乳鼠心肌成纤维细胞，分别给予不同浓度的缬沙坦(5umol·L^-1，10umol·L^-1和100umol·L^-1)与AngⅡ(10^-5mol·L^-1)共同作用心肌成纤维细胞24h，采用MTT检测心肌成纤维细胞的增殖；实时定量PCR和Western blot检测TRPC1和TGF-β1基因及蛋白表达变化。结果AngⅡ(10^-5mol·L^-1)显著增加TRPC1及TGF-β1的表达；与AngⅡ组相比，加入缬沙坦24h后，心肌成纤维细胞代谢率明显降低，TGF-β1表达明显减少（P＜0．01）；TRPC1mRNA与蛋白表达也明显减少，且随缬沙坦浓度升高，降低更显著（P＜0．01）。结论AT1受体拮抗剂缬沙坦呈浓度依赖性减少TRPC1表达，从而抑制AngⅡ促心肌成纤维细胞增殖与TGF-β1表达效应。更多还原

【Abstract】 Part 1 Expressions of TRPCs in pressure overload-inducedmyocardial fibrosis in ratsObjective: To investigate the expressions of TRPCs in pressure overload-inducedmyocardial fibrosis in rats.Methods: Myocardial fibrosis was induced by coarctaion of abdominal aorta （CAA） inSprague-Dawley rats. The rats were divided into 2 groups: The sham-oprerated group andCAA group.Blood pressure, Left ventricular mass index （LVMI）, cardiac collegen volumefraction （CVF） and the expression of TRPC channels were examined after 4 weeks ofoperation.Results: Compared with sham-operated group, blood pressure, LVMI, CVF andexpressions of TRPC1 mRNA and protein were increased remarkably in CAA group.However, TRPC3, TRPC6 mRNA and protein expressions did not changed obviously intwo groups.Conclusion: The expression of TRPC1 was significantly upregulated in pressureoverload-induced myoardial fibrosis in rats, which possible played important role inpressure overload-induced myocardial fibrosis in rats. Part 2 The role of TRPC1 in cardiac fibroblasts proliferationand the expression of TGF-β1 induced by AngⅡObjective To investigate the role of TRPC1 in cardiac fibroblasts proliferation and theexpression of transforming growth factor beta 1（TGF-β1） induced by AngⅡ.Methods Cardiac fibroblasts were prepared from the ventricles of 1-3-day-oldSprague-Dawley rats. The cells were treated with various concentration of angiotensinⅡ(10^-7,10^-6, 10^-5mol·L^-1) for 24h, or treated with angiotensinⅡ(10^-5mol·L^-1) for 0, 12 and 24h,respectively. The expressions of TRPC1 and TGF-β1 were determined by real-time quantitativepolymerase chain reaction and western blot. Under high concentration of angiotensinⅡ(10^-5mol·L^-1), cardiac fibroblasts were treated with the inhibitors of the calcium for 24 hours,including SKF96365 （an inhibitor of TRPC1）, thapsigargin (an inhibitor of Ca²⁺-ATP) andverapamil (an inhibitor of L-Ca²⁺ channel). TGF-β1 was determined by real-time quantitativepolymerase chain reaction and western blot. In addition, cells were pretreated with SKF96365or thapsigargin for 30 mins, and then treated with angiotensinⅡ(10^-5mol·L^-1), the intracellularCa²⁺ was analyzed by confocal laser microscopy.Results The expressions of TRPC1 mRNA and protein increased when treated withangiotensinⅡin a concentration- and time-dependent manner. SKF96365 and thapsigarginsignificantly inhibited fibroblasts proliferation and the TGF-β1 expression in cardiacfibroblasts induced by AngⅡ(10^-5mol·L^-1) for 24 hours. Verapamil also inhibitedfibroblasts proliferation （P＜0.01）, but has no effect on TGF-β1 expression （P＞0.05）.AngiotensinⅡ(10^-5mol·L^-1) induced an increase in intracellular Ca²⁺. And pretreatmentwith thapsigargin for 30 minutes, the intracellular Ca²⁺ sustained increasing by AngⅡinthe presence of external Ca²⁺ and only a mild and transient rise initiated by AngⅡin theabsence of external Ca²⁺ in cardiac fibroblasts. And pretreatment with SKF96365 for 30mins, the intracellular Ca²⁺ concentration did not increased by AngⅡin cardiac fibroblasts.Conclusion The expression of TRPC1 increased in cardiac fibroblasts when treated with angiotensinⅡin a concentration- and time-dependent manner. AngⅡcan increaseintracellular Ca²⁺ depending on the Ca²⁺ entry through SOC. And TRPC1 may be thepotential molecular entity for SOC, which can promote the cardiac fibrosis and TGF-β1expression in cardiac fibroblasts induced by AngⅡ. SKF96365 can prevent the cardiacfibrosis by inhibiting the expression and function of TRPC1 in cardiac fibroblasts inducedby AngⅡ. Part 3 The effects of valsartan on the expression of TRPC1 incardiac fibroblastsObjective To examine the effects of valsartan on the expression of TRPC1 in culturedcardiac fibroblasts under high AngⅡlevel.Methods Cardiac fibroblasts were prepared from the ventricles of 1-3-day-oldSprague-Dawley rats. They were treated with 10^-5mol·L^-1 angiotensinⅡin the presence ofvarious concentration valsartan (100umol·L^-1, 10umol·L^-1or 5umol·L^-1) for 24 hours. Thefibroblasts proliferation was measured by MTT. The TRPC1 and TGF-β1 mRNA andprotein expression were assayed by real time PCR and Western blot.Results AngiotensinⅡincreased the expressions of TRPC1 and TGF-β1. Comparedwith the angiotensinⅡalone group, valsartan inhibited the proliferation of cardiacfibroblasts and expression of TGF-β1. In addition, the expression of TRPC1 wasobviously inhibited by valsartan in a dose dependent manner.Conclusion Valsartan may decrease the expression of TRPC1 to inhibit proliferationof cardiac fibroblasts and the expression of TGF-β1 induced by angiotensinⅡ.更多还原