丹参素对压力超负荷性心肌肥厚大鼠治疗机理的研究

目的建立压力超负荷性心肌肥厚大鼠模型并探讨丹参素防治左室肥厚的作用机制。方法采用腹主动脉部分缩窄术复制大鼠心肌肥厚模型，18只8周龄的Wistar大鼠随机分成对照组，模型组和丹参素（radix salviae miltiorrhizae，RAM）治疗组，测量大鼠尾动脉收缩压及心脏指数并检测大鼠心肌组织中超氧化物歧化酶（Superoxide dismutase，SOD）、丙二醛（Malondialdehyde，MDA）、一氧化氮（nitrcoxide，NO）和血管紧张素-Ⅱ（Angiotensin-Ⅱ，Ang-Ⅱ）的含量。结果同对照组相比，模型组大鼠SBP、心脏指数、MDA和Ang-Ⅱ含量明显增高，而NO水平和SOD活性显著降低；同模型组相比，丹参素可以降低SBP、心脏指数、MDA和Ang-Ⅱ的含量并增强心肌组织SOD的活性和NO的生成。结论丹参能有效防治压力超负荷性大鼠心肌肥厚的发生，它的作用机制与丹参调整和改善心脏局部氧自由基代谢，增加NO的生成并抑制Ang-Ⅱ的生成有关。     

法舒地尔对压力超负荷诱导大鼠心肌肥厚的影响

目的 研究Rho激酶抑制剂法舒地尔(fasudil)对大鼠腹主动脉缩窄压力超负荷诱导的心肌肥厚的影响及机制.方法 50只雄性Wistar大鼠随机分为5组:假手术组、压力超负荷模型组、法舒地尔低剂量组、法舒地尔高剂量组及阳性对照(卡托普利)组,每组10只.除假手术组外,其他4组大鼠结扎肾上方腹主动脉制备压力超负荷模型,4周后建立心肌肥厚模型并开始给药,疗程4周.给药结束后,检测各组血流动力学指标,心脏重量指数(HW/BW)及左心室重量指数(LVW/BW);取心肌组织,经不同染色方法,观察心肌病理改变并检测心肌细胞直径(MD)和心肌胶原百分比(CVF);RT-PCR法检测心肌组织中RhoA、Rho激酶mRNA的表达.结果 与假手术组比较,模型组的LVEDP明显增加,LVSP明显下降;HW/BW、LVW/BW明显增加;MD增大(P＜0.01),CVF明显增加(P＜0.05);RhoA、Rho激酶mRNA的表达明显上调(均P＜0.01).与模型组比较,经法舒地尔及阳性药物治疗后,上述指标均有不同程度的改善(均P＜0.05,P＜0.01).结论 Rho激酶抑制剂法舒地尔可以改善心功能,抑制心肌胶原的合成及心肌纤维化,改善压力超负荷所引起的心肌肥厚.     

运动预处理对压力超负荷诱导的大鼠病理性心肌肥厚的影响

目的：探究运动预处理（EP）对压力超负荷引起的大鼠病理性心肌肥厚和心力衰竭（心衰）的影响。
　　方法：雄性6周龄SPF级SD大鼠60只分为Sham组、主动脉缩窄（TAC）组和运动预处理+主动脉缩窄（EP+TAC）组,每组20只。分别在TAC术后4周和8周时行超声心功能评价、病理检查以及心衰标志物检测来探讨EP的作用。
　　结果：超声心动图和病理检测提示两个手术组的检测指标相比Sham组均有明显变化,而且两手术组间比较, EP+TAC组的各项指标均优于TAC组,特别是在术后8周时,左心室射血分数增加15%,心脏重量指数减少15.7%和左心室重量指数减少20%（P<0.05）,差异有统计学意义。从心衰标志物心钠肽和脑钠肽信使核糖核酸（mRNA）和蛋白表达来看,与Sham组比较,TAC组在两个时间点表达量均明显升高,EP+TAC组的变化在TAC术后4周时不明显,但在术后8周时升高明显。与TAC组相比,EP+TAC组的mRNA表达量在术后4周时分别下降47%和62%,术后8周时减少44.0%和28.1%（P<0.05）;蛋白表达量术后4周时下降42.3%和48.0%,术后8周时下降21.5%、38.3%（P<0.01）,在术后8周时两手术组心衰标志物表达量差异较术后4周时减小。
　　结论：EP能改善压力超负荷诱导大鼠病理性心肌肥厚,且在早期的保护作用明显,能够延缓心衰的进程,为进一步探究作用机制提供模型基础。     

压力超负荷性心肌肥厚大鼠心肌细胞内钙激活蛋白酶活性分布的研究

目的研究大鼠心肌肥厚时,钙激活蛋白酶(Calpain)在心肌细胞胞浆和细胞核的活性分布,并探讨细胞核钙摄取的改变,以进一步阐明心肌肥厚的发生机制.方法将100只健康雄性Wistar大鼠(150～200g)随机分为对照组(n＝50)和腹主动脉缩窄组(n＝50),制备腹主动脉缩窄大鼠心肌肥厚模型、差速离心和密度梯度离心提纯心肌细胞核,荧光法测酶活性,以45Ca2+测定细胞核摄取能力.结果与对照组相比,腹主动脉缩窄组大鼠左心室重量指数增加,伴有明显的血流动力学异常,有非常显著性差异(P＜0.01);其心肌细胞核Calpain活性亦增加40.78%,有显著性意义(P＜0.05);细胞浆Calpain活性下降21.71%,有非常显著性意义(P＜0.05).对照组心肌Calpain在细胞浆的活性显著高于在细胞核的活性,有非常显著性意义(P＜0.01),而腹主动脉缩窄组心肌Calpain在细胞核的活性与在细胞浆的活性无显著差异;细胞核45Ca2+摄入量也显著增加(较对照组高28%～97%,P＜0.01).结论肥厚心肌Calpain由细胞浆向细胞核转位、细胞核内Calpain活性增加,细胞核钙摄取能力增强,提示压力超负荷时Ca2+与Calpain调节的细胞核反应水平加强,可能在介导心肌肥厚的细胞核功能调控中起重要作用.     

卡维地洛对压力超负荷大鼠肥厚心肌线粒体呼吸功能的影响及其机制

近来研究发现心肌能量产生不当可能是心肌肥厚发生及向心力衰竭发展的重要因素。本实验观察左室肥厚心肌线粒体氧化呼吸功能的改变及卡维地洛的作用，探讨卡维地洛对压力超负荷心肌线粒体能量代谢的影响及机制。     

心复康丸对压力超负荷大鼠心肌肥厚的影响

目的观察心复康丸对压力超负荷性心肌肥厚大鼠超声心动指标及心肌肥厚程度的影响。方法 Wistar雄性大鼠采用腹主动脉缩窄的方法复制心肌肥厚和心室重构的模型。造模4周后,随机分为假手术组(S组)、模型组(M组)、依那普利组(E组)、心复康丸低剂量组(L组)、心复康丸高剂量组(H组)。分别于术后8周、12周采用超声心动评价心功能,并观察心脏肥大指数变化。结果术后8周,M组大鼠出现压力超负荷介导的向心性肥厚,术后12周,M组大鼠心功能进入失代偿期,E组和H组大鼠上述病理性改变均能被抑制;此两组还具有降低心脏肥大指数的作用(P0.01)。结论心复康丸具有改善超声心动指标,延缓心肌肥厚的作用,并存在一定量效关系。     

川芎嗪对压力超负荷大鼠心肌凋亡的干预作用

目的 :观察川芎嗪对压力超负荷大鼠心肌凋亡动态变化的影响。方法 :SD大鼠 ,缩窄腹主动脉建立压力超负荷模型 ;按缩窄与否随机分为手术组 （OG）、手术 +川芎嗪干预组 （OG+ TMP）和假手术组 （SOG）。采用脱氧核苷酸末端转移酶介导的缺口末端原位标记 （TUNEL ）法 ,检测心肌细胞凋亡指数 （CAI）。结果 :OG组与 OG+ TMP组各时间点的 CAI均高于 SOG组 （CAI为 0 ）。OG组与 OG+ TMP组相比较 ,OG+ TMP组的 CAI呈显著性降低趋势（多数 P<0 .0 5）。结论 :川芎嗪不能逆转压力超负荷大鼠的心肌凋亡 ,但有减缓心肌凋亡发生的趋势 ,具有心脏保护作用     

细胞核CaMK和Calcineurin参与大鼠心肌肥厚的发生

目的：研究大鼠心肌肥厚时，钙依赖的蛋白激酶和蛋白磷酸酶在心肌细胞膜、细胞浆和细胞核的分布规律，以探讨核钙信号与核反应在心肌肥厚发生过程中的病理生理意义。方法：制备腹主动脉缩窄大鼠心肌肥厚模型、差速离心和密度梯度离心提纯心肌细胞核，同位素32P掺入法测激酶活性，无机磷生成显色法测定蛋白磷酸酶活性。结果：腹主动脉缩窄术后4周大鼠心肌显著肥厚，伴有明显的血液动力学异常。与正常对照组相比较，腹主动脉缩窄心肌肥厚组心肌细胞核钙调素蛋白激酶（CaMK）活性增加1．011倍（p〈0．001），膜升高40．16％（p〈0．001），胞浆不变（p〉0．05）；心肌细胞核钙调神经磷酸酶（Calcineurin）活性增加43．57％（p〈0．05），膜和胞浆增加无显著性（P〉0．05）。正常组和腹主动脉缩窄心肌肥厚组心肌细胞CaMK和Calcineurin活性分布为核〉膜〉胞浆（p〈0．01）。结论：腹主动脉缩窄心肌肥厚时核内钙依赖的CaMK和Calcineurin活性增加，提示压力超负荷时细胞核内钙调节的蛋白磷酸化和去磷酸化水平增高，可能在介导心肌肥厚的发生中起重要作用。     

压力超负荷下大鼠心肌细胞核钙调节系统的变化

目的：通过腹主动脉缩窄（abdominal aortic coaretation，AAC）心肌肥厚大鼠模型制备、差速离心提纯心肌细胞核、酶学方法测定Ca^2＋-ATPase活性、^45Ca^2＋同位素法测定核钙摄取和^3H放射配基受体分析心肌细胞核膜IP3R和RyR的动力学特性，初步揭示压力超负荷心肌肥厚大鼠心肌细胞核钙转导异常的环节。结果发现：AAC术后4周大鼠心肌显著肥厚，伴有明显的血流动力学异常，与对照组比较，AAC大鼠心肌细胞核Ca^2＋-ATPase活性减少51．93％（P〈0．001），但核^45Ca^2＋摄入量（核外[Ca^2＋]浓度为800-1600nmol／L时）明显增加（P〈0．05）；AAC大鼠心肌细胞核IP3R的Bmax和Kd与对照组比较分别增加1．217和2．149倍（P〈0．01），其细胞核RyR的最大结合（Bmax）较对照组减少57．8％（P〈0．001），解离常数（Kd）较对照组降低54．4％（P〈0．05）。结论为心肌细胞核Ca^2＋转运系统发生改变（Ca^2＋．ATPase活性减少、核^45Ca^2＋摄取增加、IP3R密度上调和亲和力降低，而细胞核RyR密度下调而亲和力增加），可能参与压力超负荷心肌肥厚的发生过程。     

FKBP12/12.6调控心肌兰尼碱受体的研究进展

某些心血管疾病如心律失常、心力衰竭等与心肌肌浆网兰尼碱受体2(RyR2)功能密切相关.FKBP12/12.6作为RyR2的关键调控蛋白,在稳定RyR2的结构及维持其功能的过程中具有重要作用.通过修复FKBP12/12.6与RyR2之间的相互作用可以改善RyR2功能,达到治疗作用.针对不同发病机制,靶向修复FKBP12/12.6与RyR2之间的相互作用,将成为未来治疗心血管疾病的重要突破点.     

肝脏X受体调控小鼠心肌细胞肥大性生长

目的 研究肝脏X受体(LXR)在肥厚心肌中表达的变化及其对心肌细胞肥大性生长的影响.方法 8周龄的野生型小鼠随机分为2组,即手术组和假手术组.两组小鼠分别接受主动脉缩窄术或假手术,术后2周进行各项指标检测,如心脏重/体重、心肌组织病理检测、分子生物学检测等;同时进行乳鼠心肌细胞体外培养,用血管紧张素(Ang)Ⅱ诱导心肌细胞肥大性生长,并与LXR激动剂T0901317共孵育,通过检测心肌细胞蛋白质合成率、分析细胞形态及肥大基因表达等,探讨LXR对体外心肌细胞肥大性生长的调控作用.结果 病理及分子生物学检测证实主动脉缩窄术成功的构建了心肌肥厚的小鼠模型.手术组小鼠心肌组织中LXRα的蛋白及mRNA表达均显著高于假手术组(P均<0.05),而LXRB的表达差异无统计学意义.体外研究表明,LXR激动剂T0901317呈剂量依赖性地抑制由AngⅡ诱导的心肌细胞肥大,表现在T0901317治疗组的心肌细胞面积、肥大基因的表达量、蛋白质合成率等均低于空白对照组(P均<0.05).结论 LXR是心肌肥厚的重要调控因子,LXR的激活能负性调控心肌细胞肥大性生长.     

外源性钙调素入核转运及其在大鼠心肌肥厚时的变化

目的　探讨大鼠心肌细胞核对外源性钙调素入核转运的调节机制及其在大鼠心肌肥厚时的变化。方法　制备腹主动脉缩窄心肌肥厚大鼠模型、差速离心提纯心肌细胞核、酶学方法测定钙 ATP酶活性、荧光分光光度计测定荧光标记钙调素向细胞核转入量。结果　离体纯化的大鼠心肌细胞核在ATP存在下 ,外源性钙调素经核孔向核内转运量具有显著钙离子浓度依赖性 ,随核外钙离子浓度的增加而递增 (P <0 0 5 )。在钙离子浓度为 10 -3 mol/L时 ,钙 ATP酶抑制剂thapsigargin (5μmol/L)、兰尼碱受体拮抗剂钌红 (rutheniumred ,5 0 μmol/L)和IP3 受体拮抗剂肝素 (10 μg/ml)使外源性钙调素的细胞核孔转运分别降低 90 %、2 0 %和 89% (P <0 0 5 )。腹主动脉缩窄术后 4周大鼠心肌显著肥厚 ,伴有明显的血流动力学异常 ,与对照组相比 ,腹主动脉缩窄心肌肥厚大鼠外源钙调素入核转运明显减少 (P <0 0 5 ) ,心肌细胞核钙 ATP酶活性显著下降 (P <0 0 0 1)。结论　外源性钙调素入核转运可能受核外钙离子浓度和核钙摄取、释放系统所调节 ,心肌肥厚时 ,钙调素入核转运减少、心肌细胞核钙 ATP酶活性下降 ,可能在相对稳定核功能紊乱的调节中起负性反馈作用。     

Polyamine and nucleic acid metabolism in myocardial hypertrophy of the overloaded heart

The metabolism of polyamines and nucleic acids in the hearts of rats undergoing physical activity for 2 hours once daily for 5 days has been studied. The results show a significant rise of the specific radioactivity of the polyamines (spermine and spermidine); this phenomenon reaches its peak on the second day of muscular activity. Under the same experimental conditions, the enzymic activity of amine-oxidase was evaluated, and increased on the second day of exercise; after reaching the maximum level, it remained constant until the end of the experiment. The specific activity of RNA of all the sub-cellular fractions of the heart showed a progressive increase with the duration of muscular activity. Experiments carried out with the perfused heart showed that spermine, at the concentration of 0.3 mm, stimulated the incorporation of [³H]ribose into RNA. The results suggest that the polyamines may be involved in the mechanism of myocardial RNA synthesis.     

组蛋白脱乙酰基酶2在大鼠心肌肥大中的作用

目的研究组蛋白脱乙酰基酶2(Histonedeacetylase2,HDAC2)在腹主动脉缩窄所致大鼠压力负荷性心肌肥大模型中的作用,丙戊酸钠对心肌肥大发展和HDAC2表达的影响。方法将雄性Wistar大鼠随机分为假手术组、心肌肥大组和丙戊酸钠治疗组,动物分别于14d和28d处死。检测心脏系数、心肌组织HE染色及β-肌球蛋白重链(β-myosinheavychain,β-MHC)mRNA表达。应用RT-PCR和免疫组化方法检测HDAC2表达。结果治疗组心脏系数和β-MHCmRNA表达水平较肥大组显著下降;肥大组心肌细胞肥大的病理改变较治疗组显著;14d和28d时(×400)HDAC2蛋白质免疫组化染色阳性细胞核平均数,治疗组与肥大组相比分别下降34.18%和36.24%,P<0.05;在mRNA水平上各组间差异无统计学意义,P>0.05。结论HDAC2参与大鼠心肌肥大的发病过程,丙戊酸钠抑制HDAC2蛋白质表达及心肌肥大的发展。     

压力负荷下缬沙坦对钙调神经磷酸酶介导心肌肥大通路的影响

目的 :探讨压力超负荷模型下血管紧张素 （ Ang ）受体拮抗剂缬沙坦对钙调神经磷酸酶 （ Ca N）介导心肌肥大通路的影响及 Ang 的致心肌肥厚作用。方法 :腹主动脉缩窄法建立大鼠压力超负荷模型 ,放射免疫法检测血浆、心肌 Ang 浓度 ,Western Blot检测心肌 Ca N,活化 T细胞核因子 （ NFAT3 ）蛋白表达 ,发色底物法检测 Ca N比活性 ,并测定左室重量指数。结果 :缬沙坦组血浆 Ang 浓度高于对照组 （ P<0 .0 5 ） ,心肌 Ang 浓度则相反 （ P<0 .0 5 ） ,缬沙坦组 Ca N表达及活性低于对照组 （ P<0 .0 1） ,NFAT3 表达低于对照组 （ P<0 .0 5 ） ,两组各项指标与假手术组相比均差异显著。结论 :Ang 参与激活压力负荷下钙调神经磷酸酶通路 ,缬沙坦间接干预钙调神经磷酸酶介导通路并抑制心肌肥厚的形成     

Serotonin responsiveness through 5-HT2A and 5-HT4 receptors is differentially regulated in hypertrophic and failing rat cardiac ventricle

Cardiac ventricular responsiveness to serotonin appears in rat postinfarction congestive heart failure (CHF), mainly mediated by 5-HT(4) receptors in chronic dilated CHF and 5-HT(2A) receptors in acute CHF. To differentiate between the effects of left ventricular (LV) hypertrophy and failure on 5-HT(2A)- and 5-HT(4)-mediated inotropic serotonin response, male Wistar rats with increasing LV hypertrophy (AB1-3) and failure (ABHF) 6 weeks after banding of the ascending aorta were screened for contractile function in vivo (echocardiography) and ex vivo in LV papillary muscles, and mRNA expression level determined by RT-PCR. Both AB1-3 and ABHF displayed LV hypertrophy and remodelling. In ABHF, systolic LV and left atrial diameter increased and cardiac output decreased compared to AB3. Serotonin induced a positive inotropic response (PIR) in papillary muscles correlated with the degree of hypertrophy reaching a maximum in ABHF. Both 5-HT(2A) and 5-HT(4) receptors contributed to the PIR. The 5-HT(2A) contribution increased with increasing hypertrophy, and the 5-HT(4) contribution increased upon transition to heart failure. No 5-HT(2B)-mediated PIR was observed, consistent with increased 5-HT(2B) mRNA only in non-cardiomyocytes. The 5-HT(2A), 5-HT(2B) and 5-HT(4) mRNA levels increased in AB1-3 and increased further in ABHF compared to AB3, but did not correlate with degree of hypertrophy. 5-HT(2A) mRNA was also increased in LV of terminally failing human hearts. In conclusion, functional 5-HT(2A) and 5-HT(4) receptors are differentially induced in LV hypertrophy and failure. While the 5-HT(2A)-mediated PIR is linearly correlated with the degree of hypertrophy, the 5-HT(4)-mediated PIR seems to increase with LV dilatation, as also seen in postinfarction CHF.     

Age and hypertrophy related changes in contractile post-rest behavior and action potential properties in isolated rat myocytes

“Physiological” aging as well as early and progressive cardiac hypertrophy may affect action potential (AP) pattern, contractile function, and Ca²⁺ handling. We hypothesize that contractile function is disturbed in hypertrophy from early stages and is differently affected in aged myocardium. In vivo function, cardiomyocyte contractile behavior and APs were compared in Wistar-Kyoto (WIS) rats and spontaneously hypertensive rats (SHR) at different ages and degrees of hypertrophy (3–4, 9–11, 20–24 months). Post-rest (PR) behavior was used to investigate the relative contribution of the sarcoplasmic reticulum (SR) and the Na/Ca exchanger (NCX) to cytosolic Ca²⁺ removal. APs were recorded by whole-cell current-clamp and sarcomere shortening by video microscopy. Cyclopiazonic acid was used to suppress Ca²⁺ ATPase (SERCA) function. Heart weight/body weight ratio was increased in SHR versus WIS within all age groups. Myocyte steady state (SS) shortening amplitude was reduced in young SHR versus WIS. Aging led to a significant decay of SS contractile amplitude and relengthening velocity in WIS, but the PR potentiation was maintained. In contrast, aging in SHR led to a decrease of PR potentiation, while SS contraction and relengthening velocity increased. APD_50% was always prolonged in SHR versus WIS. With aging, APD_50% increased in both WIS and SHR, but was still shorter in WIS. However, in old WIS the late AP portion (APD_90%) was prolonged. Ca²⁺ handling and AP properties are disturbed progressively with aging and with increasing hypertrophy. Decreased amplitude of shortening and velocity of relengthening in aged WIS may be attributed to reduced SERCA function. In SHR, an increase in SR leak and shift towards transmembraneous Ca handling via NCX may be responsible for the changes in contractile function. A prolonged APD_90% in aged WIS may be an adaptive mechanism to preserve basal contractility. Therefore, the effects on contractile parameters and AP are different in hypertrophy and aging.     

Normal heart rhythm is initiated and regulated by an intracellular calcium clock within pacemaker cells

For almost half a century it has been thought that the heart rhythm originates on the surface membrane of the cardiac pacemaker cells and is driven by voltage-gated ion channels (membrane clocks). Data from several recent studies, however, conclusively show that the rhythm is initiated, sustained, and regulated by oscillatory Ca(2+) releases (Ca(2+) clock) from the sarcoplasmic reticulum, a major Ca(2+) store within sinoatrial node cells, the primary heart's pacemakers. Activation of the local oscillatory Ca(2+) releases is independent of membrane depolarisation and driven by a high level of basal state phosphorylation of Ca(2+) cycling proteins. The releases produce Ca(2+) wavelets under the cell surface membrane during the later phase of diastolic depolarisation and activate the forward mode of Na(+)/Ca(2+) exchanger resulting in inward membrane current, which ignites an action potential. Phosphorylation-dependent gradation of speed at which Ca(2+) clock cycles is the essential regulatory mechanism of normal pacemaker rate and rhythm. The robust regulation of pacemaker function is insured by tight integration of Ca(2+) and membrane clocks: the action potential shape and ion fluxes are tuned by membrane clocks to sustain operation of the Ca(2+) clock which produces timely and powerful ignition of the membrane clocks to effect action potentials.