界嵴组织结构与电传导特性增龄性改变的研究

目的研究界嵴组织连接蛋白43(Cx43)的表达、细胞形态、胶原含量与电传导特性的关系及其增龄性变化,探讨其在老年性房性心律失常中的意义.     

犬右室流出道快速起搏后急性期缝隙连接蛋白43的重构

目的采用快速心室流出道起搏制作犬急性流出道室性心动过速(VT)模型,观察心室肌缝隙连接蛋白43(Cx43)含量和分布的改变。方法20只犬随机分为对照组和VT组。将刺激电极放置右室流出道心外膜,对照组不予快速起搏,VT组以180次/分频率行快速起搏模拟VT,起搏120min后开胸取流出道间隔部的左室侧和右室侧心肌组织,用Western blot检测Cx43的含量,用免疫荧光抗体标记激光共聚焦显微镜检测Cx43的分布。结果VT组左室侧和右室侧心肌组织Cx43含量较对照组心肌组织明显降低,端端分布减少(左、右室侧荧光斑面积分别为0.45±0.09μm2/μm3 vs 2.29±0.21μm2/μm3;0.26±0.12μm2/μm3 vs 1.46±0.25μm2/μm3;P均<0.01),侧侧分布相对增加,以细胞间端端连接减少为主,二者均呈现不均一分布。结论快速右室流出道起搏可致右室流出道心肌Cx43的重构。     

窦房结组织及L-型电压门控钙通道蛋白表达的增龄性变化

为了检测窦房结不同区域L 型电压门控钙通道蛋白在窦房结增龄性中的变化 ,进一步阐明病窦综合征的病因及发病机制 ,我们采用异硫氰酸荧光素标记的链霉亲和素 生物素复合物技术 ,利用激光共聚焦显微镜测定幼年兔组 (1～ 2周龄 )、成年兔组 (5～ 6月龄 )和老年兔组 (40～ 70月龄 )窦房结组织不同区域L 型电压门控钙通道蛋白荧光强度。结果 :光镜下 ,幼年兔组的窦房结组织细胞最密集 ,成年兔次之 ,老年兔最少 ,老年兔有细胞核固缩、裂解现象 ,幼年组、成年组和老年组细胞数分别为 :2 6 .4 0± 3.2 7,15 .6 0± 2 .88,11.10± 1.91,其中两两比较 ,均有显著性差异 ;三个年龄组的兔窦房结组织的L 型电压门控钙通道蛋白荧光强度在外周区与中心区均有显著性差异 ,除了成年组 ,余年龄组的交界区与中心区表达也有明显差异 ;幼年组和成年组在窦房结中心区表达的L 型电压门控钙通道蛋白荧光强度具有显著性差异 (49.95± 5 .74vs 6 0 .5 5± 10 .5 4 ,P <0 .0 1)。结论 :兔窦房结组织细胞数随年龄增加而逐渐减少 ,并且在老年兔组出现核固缩、裂解现象 ;兔窦房结表达的L 型电压门控钙通道蛋白具有异质性 ;从出生到成年 ,兔窦房结组织中心区表达的L 型电压门控钙通道蛋白随年龄增长而增加 ,但在成年后无明显变化。     

兔窦房结HCN2通道蛋白表达的不均一性和增龄性变化

目的检测窦房结起搏电流(If)基因HCN2通道蛋白在窦房结增龄性中的变化,探讨病态窦房结综合征的病因及发病机制。方法采用SABC-FITC技术,利用激光共聚焦显微镜测定幼年兔组(1~2周龄)、成年兔组(5~6月龄)和老年兔组(40~70月龄)窦房结组织不同区域HCN2通道蛋白荧光强度。结果光镜下,幼年兔组的窦房结组织细胞最密集,成年兔次之,老年兔最少,老年兔有细胞核固缩、裂解现象,幼年组、成年组和老年组细胞数分别为:26.40±3.27,15.60±2.88,11.10±1.91,其中两两比较,差异有统计学意义;幼年、成年和老年3个年龄组的兔窦房结组织的HCN2通道蛋白荧光强度在外周区与中心区差异有统计学意义;在SAN各区域,幼年组的HCN2通道蛋白荧光强度均高于成年组和老年组(幼年组与成年组:中心区60.10±12.82对43.87±9.95,交界区66.48±14.38对51.55±10.80,外周区79.49±18.63对53.52±9.16,P<0.01;幼年组与老年组:中心区60.10±12.82对33.72±3.25,交界区66.48±14.38对40.08±4.17,外周区79.49±18.63对46.58±7.59,P<0.01)。结论兔窦房结组织细胞数随年龄增加而逐渐减少,并且在老年兔组出现核固缩、裂解现象;兔窦房结表达的HCN2通道蛋白具有不均一性;随着年龄增长,兔窦房结组织各区域表达的HCN2通道均逐渐降低。     

家兔界嵴组织电生理特征及意义

目的 研究界嵴组织电生理特征,探讨其在房性心律失常中的意义。方法 采用标准玻璃微电极技术,测量界嵴的横向和纵向传导速度。记录界嵴和梳状肌细胞跨膜动作电位(actionpotential,AP),以及异丙肾上腺素对他们的影响。结果 界嵴组织具有自发电活动。其纵向和横向传导速度分别为(58.04±5.47)、(13.26±3.07)cm/s,传导异向性(纵向/横向传导速度)为4.53±0.91。界嵴细胞AP时程较长,可见明显的平台期;梳状肌细胞平台期短,其AP形态类似三角形[APD20和APD90界嵴细胞为(28.1±3.5)、(145.3±7.1)ms,梳状肌细胞为(21.8±4.1)、(125.3±6.3)ms,P均<0.01]。正常台氏液灌流时,界嵴和梳状肌细胞无早期和晚期后除极。以4μmol/L异丙肾上腺素灌流后两者均可出现早期和晚期后除极,而且在界嵴上记录到短阵快速不规则电活动,并为0.1 mmol/L维拉帕米所终止。结论 界嵴组织具有自发电活动,在一定条件下可产生触发活动,它是心房内各向异性传导的典型。界嵴参与各种房性心律失常的发生和发展,可能与其电生理基础有关。     

增龄对犬肺静脉缝隙连接蛋白的影响

目的探讨增龄对犬肺静脉缝隙连接蛋白数量及分布形式的影响。方法6只成年（1～2岁）及5只老年杂种犬（〉6岁），麻醉后行心内电生理检查以评价房颤的诱发率。然后取左上肺静脉的肌袖组织，用免疫荧光共聚焦显微镜观察Cx40和Cx43的表达和分布。结果所有的成年犬均未诱发出持续性房颤，而5只老年犬中有4只诱发出了持续性房颤（χ2，P〈0，05）。Cx40和Cx43的表达和分布在两组间无显著性差异。结论增龄并不影响犬肺静脉肌袖细胞间缝隙连接蛋白的表达水平和分布形式。     

大鼠窦房结功能及其HCN4通道蛋白表达的增龄性变化

目的 观察幼年、成年、老年SD大鼠窦房结功能及HCN4通道蛋白表达的增龄变化,探讨窦房结电生理重构的分子基础.方法 大鼠麻醉后测基础心率、用食管电极测量窦房结恢复时间(SNRT)、校正的窦房结恢复时间(CSNRT)、以及窦房传导时间(SACT),最后测量固有心率(IHR).用SABC-FITC免疫组化法染色测量大鼠窦房结HCN4通道蛋白荧光强度.结果 窦房结功能测定显示,大鼠基础心率及IHR随年龄的增加呈明显减慢趋势,大鼠SACT随年龄增长延长,大鼠SNRT和CSNRT在不同年龄段未发现显著差异.窦房结HCN4通道蛋白荧光强度随年龄增长呈减弱趋势.结论 窦房结HCN4通道蛋白表达增龄性减低可能是构成窦房结功能增龄减退的电生理分子基础之一.     

急性心房颤动缝隙连接蛋白40和43重构及蝙蝠葛碱的干预作用

采用快速心房起搏致家兔急性心房颤动 (简称房颤 )模型 ,观察心房肌缝隙连接蛋白 4 0和 4 3(Cx4 0、Cx4 3)含量和分布的改变以及钙通道阻滞剂蝙蝠葛碱干预的防治效果。 36只家兔随机等分为 3组 :对照组、房颤组和蝙蝠葛碱组。经颈内静脉将电极置入右房 ,对照组不予快速心房起搏 ,另两组以 6 0 0次 /分行快速起搏以诱发房颤。蝙蝠葛碱组于快速起搏前 30min按 5mg /kg静脉注射进行干预 ,另两组给予等容量的生理盐水。连续刺激并且房颤 8h后 ,开胸取右心耳组织 ,用Westernblot检测Cx4 0和Cx4 3的含量 ,用免疫荧光抗体标记激光共聚焦显微镜检测Cx4 0和Cx4 3的分布。结果 :房颤组心房肌组织Cx4 0和Cx4 3含量较对照组降低 (P均 <0 .0 1) ,端端分布减少 ,侧侧分布相对增加 ,以细胞间端端连接减少为主 ,二者均呈现不均一分布。蝙蝠葛碱组Cx4 0和Cx4 3的含量较对照组降低但差异无显著性 (P均 >0 .0 5 ) ,较房颤组升高且差异有显著性 (P均 <0 .0 5 ) ,二者分布不均一程度较房颤组减轻。结论 :快速心房起搏致急性房颤可引起缝隙连接蛋白 4 0和 4 3重构 ,快速起搏前用蝙蝠葛碱干预能有效减轻急性房颤时的缝隙连接蛋白重构。     

环孢霉素A干预钙调神经磷酸酶信号通路对持续心房起搏犬心房Cx40/Cx43表达的影响

目的: 观察钙调神经磷酸酶抑制剂环孢霉素A（CsA）对持续心房起搏（atrial tachypacing,ATP）模型犬心房中Cx40/Cx43表达分布的影响,探讨CsA抑制钙调神经磷酸酶信号通路（CaN）激活是否具有一定的抗心房重构的作用。方法: 健康杂种犬18只,随机分为对照组（sham组）、心房快速起搏组（ATP组,植入固律型单腔起搏器,以400次/min持续起搏8周）及CsA干预组(在快速心房起搏组处理因素的基础上,喂食CsA 8周),每组6只。8周后,处死所有实验犬,采用免疫荧光染色法及蛋白印迹法,检测各组实验犬心房组织中Cx40/Cx43表达及分布的情况。结果: 持续快速心房起搏8周,可导致犬左右心房中Cx40的表达明显增加（P<0.01）,但CsA干预组Cx40表达增加的程度明显小于ATP组（P<0.05）。Cx40的分布方式,ATP组和CsA干预组均呈现出明显的异质性,均有端端连接减少,侧侧连接增加的现象。Cx43蛋白表达的趋势与Cx40不同:快速起搏8周后,犬左右心房组织中Cx43的表达均明显减少（P<0.01）,但减少的程度CsA干预组小于ATP组（P<0.05）。Cx43的分布方式,ATP组及CsA干预组均表现为异质性增加,端端连接减少,侧侧连接增加。结论: CsA可减少ATP导致的Cx40/43表达的重构性变化,提示CsA可能具有一定的抑制心房重构的作用。     

心肌缝隙连接蛋白43与心血管疾病的关系

心脏缝隙连接（gap junction,GJ）是细胞间进行电化学偶联及信息交换的重要途径,是介导心脏维持正常的协调性和同步性功能的重要桥梁及特殊通道。GJ主要由连接蛋白组成,而在心肌细胞水平上主要包括连接蛋白（connexin,Cx）43、Cx40和Cx45,但各自在心脏部位的表达分布和功能上却有所不同。现已有研究报道分析在许多心血管疾病中,GJ在结构和功能上的改变或异常与主要心血管事件的发生有直接关联。Cx含量及分布的减少、GJ调控因素的影响及GJ的侧一侧连接导致传导异向性变化等,均可能使心脏整体功能活动不同程度地下降或受到抑制,从而引起心脏疾病的发生和发展。     

OVX大鼠腺垂体FS细胞中Cx43蛋白表达的共聚焦显微镜研究

目的：探讨间隙连接蛋白Cx43在去卵巢（OVX）致骨质疏松症（OP）大鼠腺垂体滤泡星形细胞（FS细胞）中的表达。方法：采用10月龄末孕产SD雌性大鼠40只,随机均分为OVX组和假性手术对照组（Sham组）,于术后6w末测量两组大鼠全身及腰椎骨密度（BMD）。取两组大鼠垂体,应用免疫荧光组织化学法结合激光扫描共聚焦显微镜（CLSCM）分析技术,检测腺垂体FS细胞中Cx43的表达。结果：术后6w末OVX组大鼠全身及腰椎BMD均明显低于Sham组值（P＜0．01,P＜0．01）。Cx43阳性荧光反应主要定位于相邻的FS细胞的胞浆中和／或胞膜上。OVX组Cx43阳性表达荧光强度和表达阳性率均显著低于Sham组（P＜0．01）。结论：OVX大鼠腺垂体FS细胞中Cx43蛋白表达下,顺能与OVX大鼠骨质疏松发生相关。     

Connexin 43 expression and distribution in compensated and decompensated cardiac hypertrophy in patients with aortic stenosis

OBJECTIVES: Gap junctions (GJ) are important determinants of conduction. In advanced heart failure alterations of the major ventricular GJ protein, connexin 43 (Cx43) are found. However, changes in Cx43 expression during the progression from compensated cardiac hypertrophy to heart failure, especially in humans, have not been studied extensively. The aim of the present study was to investigate changes in Cx43 expression and distribution in compensated and decompensated left ventricular (LV) hypertrophy in pressure-overloaded human hearts with valvular aortic stenosis (AS). METHODS: We measured Cx43 levels by Western blot and quantitative immunoconfocal microscopy of LV septum biopsies from three groups of patients with AS (group I (n=9): ejection fraction (EF)>50%; group II (n=12): EF 30-50%; group III (n=9): EF<30%). LV biopsies from six patients with mitral valve stenosis and two donor hearts served as controls. RESULTS: Only the early phase of LV hypertrophy (AS-I) was characterized by extensive Cx43 lateral staining. As compared to controls, the AS-I group showed a 44.3% increase in Cx43 protein, which was reflected in an augmented number of GJs per 100 microm(2) intercalated disc area (control: 62.5+/-6.4 vs. AS-I: 79.8+/-4, p<0.001) and an increased GJ surface density (control: 0.00547 vs. AS-I: 0.00724 microm(2)/microm(3), p<0.01). Decompensated LV hypertrophy (AS-III) was specified by reduced percentage of the Cx43 signal per myocyte area (control: 1.74% vs. AS-III: 1.31%, p<0.01) or per intercalated disc (control: 18.3% vs. AS-III: 11.3%, p<0.005). Mean GJ area and GJ number per intercalated discs in the AS-III group were decreased significantly by, respectively, 42.5% and 36.4% as compared to control. In addition, decompensated LV myocardium showed a markedly heterogeneous spatial distribution of Cx43. CONCLUSION: The quantity and spatial distribution of Cx43 differs markedly between compensated and decompensated LV hypertrophy in human patients with AS. Upregulation of Cx43 in compensated hypertrophy may represent the immediate adaptive response to increased load, whereas diminished and heterogeneous Cx43 distribution in decompensated hypertrophy may play maladaptive roles culminating in heart failure and ventricular arrhythmias.     

间隙连接通道蛋白不均一降解对心肌传导速度影响的研究

目的探讨急性短时间心肌缺血时连接蛋白43（Cx43）的降解对心肌电传导速度的影响。方法16只犬随机分为正常对照组（n=4）和缺血组（n=12），缺血组通过结扎冠状动脉1h造成急性心肌缺血，测定缺血区心肌电传导速度，应用激光共聚焦显微镜技术和荧光免疫组织化学方法对缺血心肌Cx43含量进行定量研究。结果（1）急性心肌缺血时Cx43迅速降解，心肌电传导速度明显下降；（2）缺血区各局部传导速度与该部位Cx43像素密度明显正相关；（3）出现持久传导阻滞的区域其Cx43降解程度均大于50％。结论急性短时间（1小时）缺血时Cx43的降解已经开始对心肌传导速度产生明显的影响作用，而局部心肌Cx43的严重降解将导致该区域出现持久传导阻滞。     

The rate and anisotropy of impulse propagation in the postnatal terminal crest are correlated with remodeling of Cx43 gap junction pattern

BACKGROUND: Disruptions to intermyocyte coupling have been implicated in arrhythmogenesis and development of conduction disturbances. At present, understanding of the relationship between the microscopic organization of intercellular coupling and the macroscopic spread of impulse in the normal and diseased heart is largely confined to theoretical analyses. METHODS AND RESULTS: The abundance and arrangement of gap junctions, as well as conduction properties, were assessed in terminal crest preparations isolated from the atria of neonate, weanling, and adult rabbits. We report that the connexin composition of terminal crest was uncomplicated, with Cx43 being the most prominent isoform detectable by Western blotting and immunostaining. Terminal crest myocytes showed little change in total Cx43-gap junction per cell during postnatal growth as assessed by stereology. However, marked non-uniformities emerged in the sarcolemmal distribution of Cx43-gap junctions. Cx43-gap junction area at myocyte termini increased 3.5-fold from birth to adulthood. Correlated with this change in Cx43, impulse propagation velocity parallel to the myofiber axis, as assessed by multi-site optical mapping using voltage-sensitive dye (di-4-ANEPPS), increased 2.4-fold. Conversely, the amount of Cx43-gap junctions on myocyte sides, and the conduction velocity transverse to the myofiber axis, remained relatively invariant during maturation. Hence, the increasing electrical anisotropy of maturing terminal crest was wholly accounted for by increases in conductance velocity along the bundle. This increase in longitudinal conduction velocity was correlated with changes in the sarcolemmal pattern, but not the overall density, of Cx43-gap junctions. CONCLUSIONS: This study provides the first correlative structure/function analysis of the relationship between the macroscopic conduction of impulse and the microscopic cellular organization of gap junctions in a differentiating cardiac bundle. Confirmation is provided for theoretical predictions which emphasize the importance of the cell-to-cell geometry of coupling in determining the spread and pattern of myocardial activation.     

风湿性心脏病心房颤动患者心房肌缝隙连接重构分布的研究

探讨心房颤动 (AF)患者心房肌细胞间缝隙连接 (GJ)中通道蛋白 (Cx)含量和分布变化与AF发生并维持的意义和机理。收集风湿性瓣膜病 2 2例 ,在建立体外循环心脏停跳前取少量心房组织。将心房组织制成组织切片进行免疫荧光标记 ,在激光共聚焦扫描显微镜下获取荧光图像 ,通过分析软件对获取的信号进行分析。显示单位面积GJ斑数 (Cells) ,面积 (Area) ,GJ斑荧光强度及GJ分布 ,在无AF(NAF)和持续性AF(AF)组间进行比较。结果 :①GJ中Cx4 0斑较细小且荧光较Cx4 3淡 ,荧光强度有明显差异 (P =0 .0 13)。②Cx4 3斑数目、面积及荧光强度在NAF和AF组间无差异 (P =NS)。③Cx4 0斑面积在NAF和AF组间无差异 (P =0 .5 96 ) ,但Cx4 0斑荧光强度在NAF和AF组间有显著差别 (P =0 .0 5 )。④纵切面与横切面GJ斑数之比、纵切面与横切面GJ斑面积之比 ,Cx4 0在NAF和AF组间有明显差异 (分别为P <0 .0 5 ,P <0 .0 1)。结论 :Cx4 3在慢性AF患者中变化不明显 ,可能不参与AF的重构。Cx4 0密度减低 ,并向侧边分布 ,增加各向异比率 ,可能有利于AF的产生和维持。     

缺血预处理对大鼠缺血再灌注后心房肌Cx43和Cx40的影响

目的 探讨缺血预处理对大鼠缺血再灌注后的心房肌缝隙连接蛋白43(Cx43)和缝隙连接蛋白40(Cx40)表达和分布的影响。方法 30只Wistar大鼠随机分为假手术组(或对照组,n=5)：只穿线不结扎左冠状动脉前降支。缺血再灌注组(I/R组,n=5)：给予前降支结扎30 min,再灌注120 min。早期缺血预处理组(IPC组,n=5)：行IPC处理后,余处理同I/R组。延迟IPC组(L-IPC组,n=5)：在IPC处理24h后,余处理同I/R组。早期远程缺血预处理组(RIPC组,n=5)：给予RIPC后,余处理同I/R组。延迟RIPC组(L-RIPC组,n=5)：RIPC处理24h后,余处理同I/R组。测量心房组织Cx40、43的mRNA表达、Cx40、43蛋白表达以及用免疫组化法测定Cx40、43的分布。结果 I/R组Cx43和Cx40在mRNA水平和蛋白水平均明显降低,分布无规律且侧面分布相对增加。而各种IPC方式(IPC、L-IPC、RIPC、L-RIPC)在I/R后,心房Cx43和Cx40mRNA水平和蛋白水平下降不明显,其分布多于心肌细胞闰盘处,仅少量分布于心肌细胞侧面。结论 IPC能维持I/R后的心房肌Cx43和Cx40的较高表达,并维持其空间分布相对稳定。     

急性心肌缺血时连接蛋白43迅速降解的非均一性研究

目的：探讨急性心肌缺血时心肌细胞连接蛋白43（Cx43）含量和分布的改变。方法：20只犬随机分为4组，通过结扎冠状动脉造成分别为0、1、3、6h的急性心肌缺血，应用激光共聚焦显微镜技术和荧光免疫组织化学方法对缺血心肌Cx43含量和分布的改变进行定量研究。结果：急性心肌缺血1h，Cx43像素密度较对照组减少22．2％（P＜0．01），3h减少40．0％（P＜0．01），6h减少53．8％（P＜0．01）。对照组心肌细胞端对端连接处Cx43含量约为侧对侧连接处的1．36倍，缺血6h后，侧对侧连接处Cx43含量反而为端对端连接处的1．6倍。对照组各层心肌细胞Cx43含量无显差异，缺血后，中间层心肌Cx43含量较其他层心肌Cx43含量下降更明显，差异有显性（P＜0．05或P＜0．01）。结论：急性心肌缺血时Cx43迅速降解，分布模式也发生明显的改变，各层心肌Cx43的降解程度明显不均一。     

Internalization and dephosphorylation of connexin43 in hypertrophied right ventricles of rats with pulmonary hypertension.

BACKGROUND: Altered expression and distribution of gap junctions might provide substrates for abnormal conduction and arrhythmogenesis in the heart, but little is known about the regulation of gap junctions under pathological conditions. The organization and phosphorylation state of connexin43 (Cx43) in ventricular hypertrophy will be investigated. METHODS AND RESULTS: Right ventricular (RV) hypertrophy was induced in rats by treatment with monocrotaline. Subcellular Cx43 distribution was assessed by immunoconfocal and electron microscopy. Immunolabeling of Cx43 was confined to the intercalated disks in the normal ventricular myocytes of control rats, but hypertrophied RV cells from monocrotaline-treated rats showed dispersion of Cx43 immunolabeling over the cell surface and in the cytoplasm; cytoplasmic Cx43 was increased by approximately 7-fold (n=15). The Cx43 internalization was confirmed by the double staining of monocrotaline-treated RV tissues for Cx43/wheat germ agglutinin (WGA) and Cx43/zonula occludens protein-1 (ZO-1). Electron microscopy of hypertrophied RVs showed an increase in annular gap junctions immunolabeled with Cx43. Immunoblotting revealed a significant increase in non-phosphorylated Cx43 in hypertrophied RVs (by approximately 5-fold, n=8) without changes in the total amount of Cx43. The accumulation of non-phosphorylated Cx43 in hypertrophied RVs was also recognized by immunoconfocal-microscopy with an isoform-specific antibody. CONCLUSION: Ventricular hypertrophy is associated with the dephosphorylation of Cx43 and its translocation from the intercalated disks to intracellular pools, suggesting accelerated gap junction degradation.     

Atrial distribution of connexin 40 and 43 in patients with intermittent, persistent, and postoperative atrial fibrillation

BACKGROUND: Sustained atrial fibrillation (AF) causes alterations in atrial electrical and structural properties. Conflicting data regarding the structural remodeling of the gap junction proteins connexin (Cx) 40 and 43 in human and animal studies exists. We investigated the amount and distribution of Cx40 and Cx43 in three subtypes of AF. METHODS: In 50 patients undergoing coronary artery bypass graft and/or mitral or aortic valve surgery, right atrial appendages were taken and examined with immunoconfocal microscopy. Retrospectively, four groups were built: (1) sinus rhythm pre- and postoperative (SR, n=20), (2) intermittent AF, but SR prior to surgery (intAF, n=6), (3) postoperative AF (popAF, n=12), and (4) persistent AF, at least 3 month prior to surgery (persAF, n=12). We analyzed the amount of Cx40 and Cx43 and the degree of fibrosis in three randomly selected areas of each sample. RESULTS: As compared with SR, the amount of Cx40 was significantly reduced by 53% in persAF. The distribution pattern of Cx40 was heterogeneous in patients with SR, intAF, and popAF, whereas patients with persAF showed similar densities of Cx40 in the three examined areas. We found no significant difference in the amount of Cx43 between the four groups. The distribution pattern of Cx43 was heterogeneous in all four groups. The Cx40/Cx43 ratio was significantly reduced in patients with popAF and persAF by 51% and 53%, respectively. No difference was seen in the degree of fibrosis between the four groups. CONCLUSIONS: In this study, sustained AF leads to a reduction in the amount of Cx40. Together with a specific Cx40/Cx43 ratio, this may contribute to localized conduction abnormalities, facilitating the self-perpetuation of re-entry pathways in AF. In the time course of structural atrial remodeling these changes seem to be earlier than a concomitantly developing fibrosis.     

交感神经刺激对大鼠缺血性室性心律失常的影响及其机制的探讨

目的 探讨大鼠急性心肌缺血时交感神经刺激对室性心律失常的影响及其潜在的机制.方法 结扎大鼠冠状动脉前降支制备急性心肌缺血模型后随机分组作为心肌缺血组(MI组,n=25)、缺血+交感神经刺激组(MI-SS组,n=25)、交感神经刺激+酚妥拉明+缺血组(MI-SS-Phen组,n=15)、交感神经刺激+普萘洛尔+缺血组(MI-SS-Prop组,n=15)和假手术组(SO组,n=20).心电图监测室性心律失常的发生.蛋白免疫印记法(Western blot)检测缝隙连接蛋白43(Cx43)的磷酸化蛋白及总量表达变化.逆转录聚合酶链反应(PCR)分析Cx43 mRNA的表达变化.免疫荧光观察Cx43表达分布情况.结果 结扎冠状动脉30 min内MI、MI-SS和MI-SS-Phen组分别有1、3和2只大鼠死于心室颤动(室颤);MI-SS组室性心动过速(室速)/室颤发生率(80.0%,20/25)较MI组(52.0%,13/25)明显增加(P＜0.05);与MI-SS组相比,普萘洛尔明显阻断了交感神经刺激促室速/室颤发生的作用(13.3%,2/15,P＜0.05).冠状动脉结扎30 min后,MI组磷酸化Cx43的比例较SO组显著降低(P＜0.05),但其总量并未减少(P＞0.05).与MI组相比,MI-SS组磷酸化Cx43的比例明显增加(P＜0.05),同时其蛋白总量的表达显著降低(P＜0.05);普萘洛尔显著抑制了交感神经刺激导致的Cx43蛋白降解的作用,同时抑制了缺血引起的Cx43脱磷酸化(P＜0.05).MI和MI-SS组Cx43mRNA表达均较SO组显著减少(P＜0.05).免疫荧光结果 显示,与SO组相比,MI组Cx43由端-端连接转化为侧-侧连接,而MI-SS组Cx43分布明显紊乱,不能分辨出Cx43的分布模式.结论 交感神经刺激能够促进室性心律失常的发生,可能主要与β肾上腺素受体的激活从而促进了Cx43的降解有关.