多柔比星介导的血管损伤促进主动脉夹层发生发展的机制研究

目的探讨多柔比星(Dox)介导的血管损伤在促进主动脉夹层(AD)发生发展中的作用机制。方法选取武汉大学人民医院行胸AD全弓置换患者10例为实验组,同期选择心脏移植术患者3例为对照组,2组均于术中取AD血管标本。另取3周龄雄性C57BL/6J野生型小鼠18只,随机分为3组,每组6只,对照组(WT组)、β氨基丙腈酯(BAPN)组(第3周开始饲喂含0.25%BAPN小鼠维持饲料)、BAPN+Dox组(根据体质量每周腹腔注射3mg/kg Dox,连续5周,第3周开始饲喂饲料同BAPN组),5周后,游离小鼠主动脉,4%多聚甲醛固定,石蜡包埋,切片。免疫组织化学及Western blot检测组织P53蛋白表达,TUNEL染色检测细胞凋亡情况。结果实验组P53蛋白较对照组明显升高(0.76±0.05 vs 0.39±0.11),凋亡细胞明显增多[(38.3±8.7)%vs (12.6±1.2)%](P0.01)。BAPN+Dox组死亡率明显高于BAPN组(100.0%vs 66.7%);BAPN+Dox组组织P53蛋白较BAPN组显著升高;VSMC凋亡明显增多,且2组P53蛋白和血管平滑肌细胞(VSMC)凋亡均较WT组明显升高(P0.01)。结论 Dox介导的血管损伤可能通过诱导VSMC凋亡,促进AD发生发展。     

催产素引产的合理应用与观察

催产素又叫缩宫素,其主要作用机理为促进子宫平滑肌收缩,在妊娠早、中期催产素的作用仅产生局限性宫缩活动,不能传及整个子宫,也不能使宫颈扩张.足月妊娠时,肌细胞趋于协调,催产素才能发挥催产作用.在引产过程中使用得当则安全有效,反之,可危及母子生命.下面介绍一下催产素在引产过程中怎样合理应用与观察.     

Characteristics of the Nonselective Cation Current （NSCCs） in Rabbit Left Ventricular Epicardial, Midmyocardial and Endocardial Myocytes

Objectives Recent studies have described regional differences in the electrophysiology and pharmacology of ventricular myocardium in canine, feline, rat, guinea pig, and human hearts. This has been shown to be due to a smaller IKs and a lager sodium-calcium exchange current (INa-Ca) and late INa in M region (deep subepicardial to midmyocardial). Studies from our laboratory have found a new repolarization current-nonselective cation current (NSCCs) existing in rabbit right ventricular myocytes. Methods We examined the characteristics of NSCCs in epicardial, M region, and endocardial cells isolated from the rabbit left ventricle with standard microelectrode and whole-cell patch-clamp techniques. The permeability to Na , K , Li , Cs but not to Cl- indicating that it was a nonselective cation current. Gd3 (0.1 mmol/l) and La3 (0.1 mmol/l) can block the current markedly. Results Further characterization of NSCCs was significantly smaller in M cells than in epicardial and endocardial cells. NSCCs current density was significantly smaller in M cells than in epicardial and endocardial cells. With repolarization to -80 mV, INs current density was (-0.44±0.05) PA/PF in endocardial cells, (-0.12±0.05) PA/PF in M cells and (-0.28±0.07) PA/PF in epicardial cells; and with repolarization to 30 mV, INs current density was (1.09±0.29) PA/PF in endocardial cells, (0.38±0.09) PA/PF in M cells and (0.91±0.32) PA/PF in epicardial cells. Conclusions Transmural dispersion of repolarization was due to the heterogeneity of NSCCs in rabbit left ventricle epicardial, endocardial myocytes and M cells. These findings may advance our understanding of the ionic basis for our understanding of factors contributing to the development of cardiac arrhythmias.     

热休克蛋白90对大鼠缺氧心肌细胞丝氨酸苏氨酸蛋白激酶表达的影响

目的探讨内源性热休克蛋白90（HSP90）在缺氧心肌细胞丝氨酸苏氨酸蛋白激酶（AKT）相关信号通路中的作用。方法建立新生Wistar大鼠心肌细胞缺氧模型，将细胞分为正常组、缺氧组、加入HSP90特异性阻断剂格尔德霉素后再缺氧组（格尔德霉素＋缺氧组）。于缺氧后1、3、6、12、24、48h用噻唑蓝法检测心肌细胞的活力；缺氧24h，原位缺口末端标记法检测心肌细胞凋亡指数（AI）；缺氧1、3、6、12、24h，蛋白质印迹法检测大鼠心肌细胞中内源性HSP90及AKT表达水平。结果（1）缺氧24、48h，缺氧组、格尔德霉素＋缺氧组细胞活力均较正常组明显下降（P〈0．05）；格尔德霉素＋缺氧组细胞活力缺氧12h即开始明显下降，缺氧48h时明显低于缺氧组（P〈0．05）。（2）缺氧24h，缺氧组细胞AI为（10．7±1．2）％，明显高于正常组[（1．9±0．3）％．P〈0．05]；格尔德霉素＋缺氧组细胞AI为（26、3±5．3）％，明显高于缺氧组（P〈0．01）。（3）缺氧12h，缺氧组心肌细胞内源性HSP90及AKT表达水平高于正常组与格尔德霉素＋缺氧组；缺氧24h，缺氧组有所下降．格尔德霉素＋缺氧组则下降更明显。结论内源性HSP90对维持心肌细胞的活力有重要作用．缺氧心肌细胞AKT表达水平可受内源性HSP90表达水平的影响。     

黄连素对培养鸡胚心室肌细胞钙单通道电流的影响

在培养的鸡胚心室肌细胞上，我们采用膜片钳技术的细胞贴附式构型，研究了黄连素（Ｂｅｒｂｅｒｉｎｅ，ＢＲ）对细胞膜钙单通道电流的影响。结果表明：ＢＲ可使心室肌细胞膜钙单通道电流明显增加；钙通道可利用率增加１１４．２％（Ｐ＜０．００１）；钙通道开放概率增加７５．３％（Ｐ＜０．０５）。用心得安阻断β受体或用异搏定阻断钙通道，均可逆转ＢＲ的上述作用。以上提示：①ＢＲ是一种钙通道激活剂；②ＢＲ对钙通道的调节作用依赖于β受体介导的磷酸化过程。     

Anti-inflammatory effect of erythropoietin pretreatment on cardiomyocytes with hypoxia/reoxygenation injury and the possible mechanism

Objective： To investigate the anti-inflammatory effect of erythropoietin （EPO） pretreatment on cardiomyocytes exposed to hypoxialreoxygenation injury （H/R） and explore the possible mechanism.
Methods： The cultured neonatal rats＇ ventricular cardiomyocytes were divided randomly into 4 groups, control group （C group）, EPO pretreatment group （E group）, EPO and pyrrolidine dithiocarbamate （PDTC） pretreatment group （EP group） and PDTC pretreatment group （P group）. After 24 hours＇ pretreatment, the cardiomyocytes were exposed to H/R. After pretreatment and H/R, the expression of tumor necrosis factor- α （TNF- α ） gene in all the groups was detected by RT-PCR and Western blot. The nuclear factor- κ B （NF- κB） activity was detected by electrophoretic mobility shift assay （EMSA） and the inhibitor- κB α （Ⅰ- κB α） protein level was detected by Western blot.
Results： The decrement of Ⅰ- κB a protein and the increasing NF- KB activity were found in cardiomyocytes pretreated with EPO before H/R compared to other groups （t=3.321, 4.183, P〈0.01）. However, after H/R, NF- κB activity and expression of TNF- α gene were significantly reduced, Ⅰ- κB a protein expression was increased in cardiomyocytes of E group compared to other groups （t=-3.425, 3.687, 3.454, P〈0.01）. All theses changes caused by EPO pretreatment were eliminated by the intervention of PDTC （an antagonist to NF- κB） during pretreatment.
Conclusions： EPO pretreatment can inhibit the activation of NF- κB and upregulation of TNF- α gene in cardiomyocytes exposed to H/R through a negative feedback of NF- κB signaling pathway, and thus produces the anti-inflammatory effect. This might be one of the ways EPO produces the anti-inflammatory effect.     

缺氧早期大鼠心肌细胞微管损害的观察

目的 了解缺氧早期心肌细胞微管损害程度。方法将分离培养的Wistar大鼠心肌细胞分为正常组、缺氧组（建立缺氧细胞模型并设缺氧10、20、30、60min为观察时相点）。用激光共聚焦显微镜及扫描电镜观察2组细胞微管分布、形态变化，对微管蛋白荧光强度进行半定量分析．用蛋白质印迹法检测2组细胞游离d微管蛋白的表达。结果 与正常组比较，缺氧10min后，缺氧组细胞微管念珠状结构消失，但排列尚有规律、数量无明显减少；缺氧20min不仅念珠状结构消失，而且微管排列散乱，远离胞核区出现微管缺失；缺氧30、60min时微管发生扭曲、断裂，纹理紊乱，完全丧失规律性。缺氧组心肌细胞微管蛋白荧光强度较正常组下降，且随缺氧时间延长愈加明显；缺氧组心肌细胞内游离的α微管蛋白表达（缺氧10min为46644±145）高于正常组（13357±98），两组比较，差异有统计学意义（P〈0．01），随缺氧时间的延长此升高趋势愈加明显。结论在缺氧状态下，心肌细胞微管发生解聚时间较早，其结构和分布规律被破坏。微管解聚在缺氧所致心肌细胞早期病理损害中的作用值得深入研究。     

自体心房肌细胞移植改善缺血后心脏功能的研究

细胞移植是治疗损伤心脏的潜在疗法。本研究旨在探讨自体心房肌细胞移植对心脏功能的影响,现将结果报道如下。 一、材料和方法 1.麻醉及术后处理:雄性成年Lewis大鼠16只,随机分为实验组、对照组各8只。用成巴比妥钠(30 mg/kg体重)、盐酸氯胺酮(22mg/kg体重)腹腔注射麻醉。气管插管,呼吸机正压呼吸,频率为60次/min,氧流量2 L/min,潮气量3 ml。