高血压大鼠心脏中缝管连接蛋白的表达及连接结构观察

目的　为临床高血压心脏病的相关研究提供形态学依据。方法　 Dahl盐敏感高血压大鼠于生后 5w开始喂 8%高盐饲料 ,分别于 9、1 1、1 3周龄处死 ,采用透射电镜及免疫组化方法对大鼠心肌细胞的连接结构及缝管连接蛋白 Cx43、Cx40的含量进行研究。结果　心肌细胞的连接结构闰盘似山峰样 ,台阶消失 ,缝管连接位于突起之间 ;实验组 Cx43含量较相应对照组显著减少 (9周龄 P<0 .0 5;1 1、1 3周龄 P<0 .0 1 ) ,分布紊乱 ;Cx40含量在早期 (9周龄 )时显著减少 (P<0 .0 1 ) ,随后显著增加 (P<0 .0 1 )。结论　缝管连接分布的紊乱及 Cx43含量的下降可能在高血压心脏病心律失常的发生上起了重要作用 ,而 Cx40含量增加可能是增加传导速度的一个补偿机制。     

不同运动量游泳运动对大鼠左心室心肌闰盘结构和间隙连接蛋白43的影响

目的:探讨不同运动量游泳运动对大鼠左心室心肌闰盘结构和间隙连接蛋白43(Cx43)的影响,以期为运动对心肌的生理和病理变化研究提供参考资料。方法:SD大鼠分为不同运动量运动组和力竭运动组,前者进行12周的低、中和高运动量游泳运动,后者进行1次力竭游泳运动。运动后取左心室心肌组织进行常规透射电镜样品制备和Cx43免疫组化染色,电镜观察左心室心肌闰盘结构变化,光镜和图像分析方法对Cx43的分布和含量改变进行研究。结果:安静对照组大鼠左心室心肌细胞闰盘结构清晰,由粘着连接、桥粒和间隙连接组成,呈阶梯状排列,Cx43主要分布在闰盘处。低和中运动量大鼠闰盘结构、Cx43分布和含量与安静对照组差异不大。高运动量大鼠闰盘连接间隙明显增宽,Cx43在心肌细胞侧对侧连接增加,含量明显降低。力竭运动大鼠闰盘结构紊乱,局部断裂或折迭;力竭后即刻Cx43含量与安静对照组差异不明显,随着力竭运动后时间的延长,Cx43含量显著降低。结论:高运动量和力竭运动可以导致左心室心肌闰盘结构破坏,Cx43降解和分布模式改变。     

神经干/祖细胞移植对脑损伤导致的胶质细胞活化有调节作用并有助于移植细胞与宿主胶质细胞间缝隙连接的建立

移植神经干/祖细胞有助于受损脑组织形态和功能的恢复。移植部位的微环境及移植细胞与宿主细胞间的通讯在神经干/祖细胞移植的神经保护机制中有重要意义。笔者既往研究显示,对中枢轴索损伤动物进行神经干/祖细胞移植有助于恢复损伤神经元的电活动及突触联系,并可增加神经营养因子的释放。本研究拟观察移植的神经干/祖细胞与宿主胶质细胞间的解剖关系,以探讨神经干/祖细胞移植的神经保护作用的可能机制。从新生大鼠的脑室下区提取神经干/祖细胞移植到内侧纵束横断伤模型大鼠脑内。移植后8周取脑进行相关检测。免疫组化检测结果显示,与未移植神经干/祖细胞的大鼠相比,移植了神经干/祖细胞的大鼠脑内更多的小胶质细胞被激活。移植的神经干/祖细胞聚集在激活的小胶质细胞和星形胶质细胞附近。缝隙连接蛋白CX-43表达在损伤部位的神经干/祖细胞和胶质细胞上,且较多的存在于移植细胞和胶质细胞相连接的部位。移植的神经干/祖细胞和宿主胶质细胞及宿主小胶质细胞间均形成了缝隙连接,但移植的神经干/祖细胞和宿主胶质细胞间的缝隙连接较多。本研究结果显示,神经干/祖细胞移植对脑损伤导致的胶质细胞活化有调节作用,并可能通过在移植细胞和宿主细胞间建立缝隙连接来调节细胞间的通讯,这可能是细胞移植的神经保护作用的机制之一。     

Cardiac conduction is required to preserve cardiac chamber morphology

Electrical cardiac forces have been previously hypothesized to play a significant role in cardiac morphogenesis and remodeling. In response to electrical forces, cultured cardiomyocytes rearrange their cytoskeletal structure and modify their gene expression profile. To translate such in vitro data to the intact heart, we used a collection of zebrafish cardiac mutants and transgenics to investigate whether cardiac conduction could influence in vivo cardiac morphogenesis independent of contractile forces. We show that the cardiac mutant dco^s226 develops heart failure and interrupted cardiac morphogenesis following uncoordinated ventricular contraction. Using in vivo optical mapping/calcium imaging, we determined that the dco cardiac phenotype was primarily due to aberrant ventricular conduction. Because cardiac contraction and intracardiac hemodynamic forces can also influence cardiac development, we further analyzed the dco phenotype in noncontractile hearts and observed that disorganized ventricular conduction could affect cardiomyocyte morphology and subsequent heart morphogenesis in the absence of contraction or flow. By positional cloning, we found that dco encodes Gja3/Cx46, a gap junction protein not previously implicated in heart formation or function. Detailed analysis of the mouse Cx46 mutant revealed the presence of cardiac conduction defects frequently associated with human heart failure. Overall, these in vivo studies indicate that cardiac electrical forces are required to preserve cardiac chamber morphology and may act as a key epigenetic factor in cardiac remodeling.     

扶正化瘀胶囊对心肌梗死大鼠心肌缝隙连接蛋白43表达的影响

目的研究扶正化瘀胶囊对心肌梗死大鼠心肌缝隙连接蛋白43(connexin43,CX43)表达的影响。方法SD雄性大鼠随机分为假手术组、模型组以及扶正化瘀胶囊组和卡托普利组,每组各6只,采用结扎左冠状动脉前降支造成心肌梗死。术后10d开始灌胃给药,持续8周。用免疫组织化学方法观察心肌CX43表达的变化。结果在心肌梗死区域内,模型组与假手术组比较,CX43排列紊乱,阳性表达面积、平均光密度值和积分光密度均显著低于假手术组(P<0.01)。在梗死边缘区,扶正化瘀胶囊组CX43平均光密度值高于模型组(P<0.01),积分光密度高于模型组(P<0.05),CX43排列紊乱有所减轻,阳性表达面积与模型组无统计学意义。卡托普利组CX43平均光密度值高于模型组(P<0.01),积分光密度和阳性表达面积均高于模型组(P<0.05),CX43排列紊乱也有减轻。结论扶正化瘀胶囊能够部分改善心肌梗死大鼠心肌的CX43重构。     

晚期扩张型心肌病患者心肌Cx43蛋白表达的研究

目的:探讨晚期扩张型心肌病(DCM)患者心肌连接蛋白43(Cx43)表达变化及其意义。方法:运用免疫组化和图像分析技术,对5例晚期DCM患者和4例因其他心脏疾病(A对照组)行心脏移植手术切除的心脏及4例机械性损伤死者(B对照组)的左心室心肌Cx43蛋白表达进行定位和定量研究。结果:DCM患者心肌Cx43蛋白表达较清晰,主要位于心肌闰盘处,呈条状、斑点或颗粒状散在分布,有的散在分布于心肌细胞侧边;A对照组表达清楚,位于心肌闰盘处,主要呈条状,少数呈斑点状散在分布,而心肌侧边分布很少;B对照组阳性着色较淡,在闰盘处呈条状分布,少有斑点状散在分布,心肌侧边几无表达。定量检测和统计分析发现,DCM组心肌Cx43蛋白表达的量低于A对照组但高于B对照组。心肌Cx43蛋白表达的平均光密度,DCM组与A对照组、B对照组相比,A对照组与B对照组相比,差异均有统计学意义(P<0.01);心肌Cx43蛋白表达的S值,DCM组、A对照组、B对照组间比较,差异均无统计学意义(P>0.05)。结论:晚期DCM患者心肌Cx43蛋白表达的数量和分布均发生改变,这种变化很可能是导致DCM患者发生心律失常和心功能衰竭的病理基础。     

Atrial-selective approaches for the treatment of atrial fibrillation

Atrial-selective pharmacologic approaches represent promising novel therapeutic options for the treatment of atrial fibrillation (AF). Medical treatment for AF is still more widely applied than interventional therapies but is hampered by several important weaknesses. Besides limited clinical efficacy (cardioversion success and sinus-rhythm maintenance), side effects like ventricular proarrhythmia and negative inotropy are important limitations to present class I and III drug therapy. Although no statistically significant detrimental survival consequences have been documented in trials, constitutional adverse effects might also limit applicability. Cardiac targets for novel atrial-selective antiarrhythmic compounds have been identified, and a large-scale search for safe and effective medications has begun. Several ionic currents (I(KACh), I(Kur)) and connexins (Cx-40) are potential targets, because atrial-selective expression makes them attractive in terms of reduced ventricular side-effect liability. Data on most agents are still experimental, but some clinical findings are available. Atrial fibrillation generates a specifically remodeled atrial milieu for which other therapeutic interventions might be effective. Some drugs show frequency-dependent action, whereas others target structurally remodeled atria. This review focuses on potential atrial-selective compounds, summarizing mechanisms of action in vitro and in vivo. It also mentions favorable interventions on the milieu in terms of conventional (such as antifibrotic effects of angiotensin-system antagonism) and innovative gene-therapy approaches that might add to future AF therapeutic options.     

The Cochlear Pericytes

Objectives : Cochlear pericytes are not well characterized. The aim of this study was to further advance the characterization of cochlear pericyte location and distribution, with particular focus on pericyte‐related proteins on the capillaries of the cochlear lateral wall that are functionally integral to structure, contraction, and gap junction transport. Materials and Methods : Cochlear pericytes were identified by the immunofluorescence labeling of pericyte marker proteins, including alpha–smooth muscle actin (α‐SMA), desmin, Thy‐1, tropomyosin, and NG2, and by morphological identification, using fluorescence, electron, and differential interference contrast microscopy. Results : Pericytes were predominately found in the capillary network of the cochlear lateral wall, with considerable morphological heterogeneity across different types of microvessels. For example, pericytes on the vessels of the spiral ligament (V/SL) strongly expressed a gap junction protein, connexin 40, and were positive for α‐SMA, tropomyosin, and desmin. In contrast, pericytes on the vessels of the stria vascularis (V/SV) were positive for desmin, and were negative for α‐SMA and tropomyosin. Conclusions : The capillary networks of the cochlear lateral wall comprise a rich population of pericytes. These pericytes are morphologically heterogeneous, with protein expression potentially indicative of function.