【作者】 刘鸿；

【导师】 邱龄；

【作者基本信息】 山西医科大学 ， 心血管内科学， 2010， 硕士

【摘要】 第一部分窦房结细胞连接方式及电生理基础背景近年来,使用分子生物学技术构建生物起搏器的研究成为热点,而对窦房结生理起搏机制的深入了解对此研究有重要的意义。多种离子通道参与窦房结的自动除极,而窦房结的细胞连接方式对其实现电相互作用的同步性和传导性起着重要的作用,因此,对参与窦房结自动除极的离子流及相应的离子通道以及窦房结细胞的连接方式的研究显的尤为重要。目的总结概括对参与窦房结自动除极的离子流及相应离子通道以及窦房结细胞连接方式的研究进展。检索策略从PubMed数据库中,使用英文关键词"ion channel, sinoatrial node"、"connexin, sinoatrial node "检索了从1979年7月到2010年3月发表的相关文章。通过以下两条标准对643篇文章进行挑选和评估：①文章与窦房结细胞连接方式、窦房结起搏电生理密切相关；②文章是最新发表的,而且发表在该领域的权威杂志。文献评估文献的主要来源是关于对窦房结细胞连接方式、窦房结自动除极相关离子通道的随机对照试验。在所选的43篇文章中,5篇是综述,其它的都是基础的实验研究。资料综合①缝隙连接是窦房结细胞间的主要连接方式,缝隙连接蛋白是构成缝隙连接的分子基础,窦房结组织中以传导性差的Cx45为主,传导性高的Cx43在P-P、P-T细胞间呈阴性表达,在T-心房肌细胞呈阳性表达,从窦房结中央到界嵴Cx43从无到弱到强,在界嵴边缘Cx43表达,界嵴与窦房结外围之间有一个过渡区Cx43,Cx45同时表达。②由于传导性差的Cx45和传导性高的Cx43在窦房结分布的特点,窦房结中心部分传导性最低,向外则传导性逐渐升高。窦房结中心的起搏细胞由于低传导性Cx45的保护而不受心房肌的抑制。③窦房结的自动除极是由随时间而增长的净内向电流引起,主要由一种外向电流和两种内向电流所构成：一、延迟整流钾电流IK1通道逐渐失活所致K+外流进行性衰减；二进行性增强的内向离子流If；三钙通道的激活和钙内流。结论多种离子通道参与窦房结的自动除极,窦房结的细胞连接方式对其实现电相互作用的同步性和传导性起着重要的作用。第二部分生物起搏治疗病态窦房结综合征背景病态窦房结综合征是指窦房结及其周围组织病变和功能减退而引起一系列心律失常的综合征。传统的治疗方法是植入电子起搏器,随着分子生物学技术的发展,生物起搏为病态窦房结综合征的治疗开辟了一个全新的领域。生物起搏是指利用细胞分子生物学及其相关技术对受损的自律性节律点或特殊传导系统的细胞进行修复或替代,使心脏的起搏和传导功能得以恢复。生物起搏包括基因生物起搏,细胞生物起搏和基因工程干细胞生物起搏。目的总结概括用细胞分子生物学的方法构建生物起搏器的研究进展。检索策略从PubMed数据库中,分别使用英文关键词"biological pacemaker" and "stem cell"、"biological pacemaker" and "gene"检索了从1979年7月到2010年3月发表的相关文章。通过以下两条标准对85篇文章进行挑选和评估：①文章与生物起搏器的构建密切相关；②文章应是最新发表的,而且发表在该领域的权威杂志。文献评估文献的主要来源是关于通过基因或干细胞的方法构建生物起搏器的随机对照试验。在所选的40篇文章中,8篇是综述,其它的都是基础的实验研究。资料综合①生物起搏是利用细胞分子生物学及其相关技术对受损的自律性节律点或特殊传导系统的细胞进行修复或替代,使心脏的起搏和传导功能得以恢复。生物起搏主要包括基因生物起搏,细胞生物起搏和基因工程干细胞生物起搏三方面。②基因生物起搏的研究主要集中在三方面：一、通过转染克隆的β2受体基因,使心肌细胞膜上的β2受体表达上调,增加心脏对内源及外源性肾上腺素的反应,提高心率；二、使编码延迟整流钾电流Ik1钾通道的Kir2基因突变,从而减少超极化电流,就可使非起搏心肌细胞产生与真的起搏细胞动作电位类似的自主电活动；三、转染编码起搏电流If的超极化激活的环核苷酸门控的离子通道(HCN)基因,以诱导心室肌细胞产生自主反应的起搏功能。③干细胞生物起搏是诱导干细胞(包括有胚胎干细胞,间充质干细胞等)使其分化为具有起搏和传导功能的细胞,然后移植到心脏内重建心脏的起搏和传导功能。④基因工程干细胞生物起搏是将编码起搏电流通道的基因装载到干细胞进行移植,即构建基因修饰的干细胞。结论基因治疗和细胞治疗构建生物起搏器将成为治疗病态窦房结综合征的最理想方法。更多还原

【Abstract】 Part I The cell connection and electrophysiological basis of the sinoatrial nodeBackground Recent years, while the construction of biological pacemaker by molecular biology techniques has became hot, understanding the mechanisms of the sionatrial node pacemaker activity seems important. A variety of ion channels are involved in the spontaneous depolarization of sinoatrial node, and its cell connection plays an important role to achieve the conductivity and Synchronization of electrical interaction. Therefore, the researches of the ionic currents and related ion channels which are involved in the spontaneous depolarization and its cell connection seems more important.Objective To sum up the research advancement in ionic currents and related ion channels which are involved in the sinoatrial node spontaneous depolarization and its cell connection.Retrieval strategy The relevant articles published between July 1979 and March 2010 were searched for in Pub Med database by researcher of this article with the key words of "ion channel, sinoatrial node" or "connexin, sinoatrial node" in English.643 articles were selected and reviewed by the inclusive criteria of:①articles closely related with the ionic currents and related ion channels which are involved in the sinoatrial node spontaneous depolarization and its cell connection;②the late articles and articles in authority journals in the same field.Literature evaluation The main sources of literatures were randomized clinical trial (RCT) on the ionic currents and related ion channels which are involved in the sino atrial node spontaneous depolarization and its cell connection. Among 43 selected articles,5 were reviews, and others were elementary experimental studies.Data synthesis①Gap junction is the main connection in sinoatrial node, and the molecular basis of gap junction is connexin. Cx45 with poor conductivity is the main connexin in the sino atrial node tissue, Cx43 with high conductivity is negative between P-P、P-T cells, but positive between T-atrial cells. From the central of sino atrial node to crista terminalis, Cx43 express from nothing to weakly to strongly. Cx43 express in the edge of the crista terminalis, there is a transitive region between sinoatrial node periphery and crista terminalis, where Cx43 and Cx45 expression at the same time.②Because of the special distribution of the Cx45 with low conductivity and Cx43 with high conductivity in sinoatrial node, the conductivity is gradually increased from the central of the sinoatrial node to the periphery, and it is the lowest in the central. Thanks to the protection of the Cx45 with low conductivity, the pacemaker cells in the central of the sinoatrial node can not be inhibited from the atrial cells.③The spontaneous depolarization in the sinoatrial node is caused by an net inward current increased with time, and it is mainly composed of one kind of outward current and two kinds of inward currents:1 The delayed rectifier current Ik1 channel lose the activity gradually and the outflow of K+ reduce gradually.2 A gradually enhanced inward current If; 3 The activation of calcium channel and calcium influx.Conclusion A variety of ion channels are involved in the spontaneous depolarization of sino atrial node, and its cell connection plays an important role to achieve the conductivity and Synchronization of electrical interaction.Part II Biological Pacemaker for treatment of sick sinus syndromeBackground Sick sinus syndrome refers to the lesions and dysfunction of the sinus node and surrounding tissue which caused a series of arrhythmia. Traditional treatment is to implanted electronic pacemakers, bio-pacemaker has opened up a whole new field for sick sinus syndrome along with the development of molecular biology techniques. Bio-pacemaker refers to using Cell Molecular Biology and related technologies to repair or replace the damaged self-rhythm points or special conduction system so that the heart pacemaker and conduction function can resume, including bio-pacemaker with the use of genes, bio-pacemaker with the use of cells and bio-pacemaker with the use of genes and stem cells.Objective To sum up the research advancement in constructing biological pacemaker with molecular biology techniques.Retrieval strategy The relevant articles published between July 1979 and March 2009 were searched for in Pub Med database by researcher of this article with the key words of "biological pacemaker" and "stem cell"、"biological pacemaker" and "gene" in English.85 articles were selected and reviewed by the inclusive criteria of:①articles closely related with the construction of biological pacemaker;②the late articles and articles in authority journals in the same field.Literature evaluation The main sources of literatures were randomized clinical trial (RCT) on biological pacemaker by gene or stem cells. Among 40 selected articles,8 were reviews, and others were elementary experimental studies.Data synthesis①Bio-pacemaker refers to using Cell Molecular Biology and related technologies to repair or replace the damaged self-rhythm points or special conduction system so that the heart pacemaker and conduction function can resume, including bio-pacemaker with the use of genes, bio-pacemaker with the use of cells and bio-pacemaker with the use of genes and stem cells.②The studies of gene therapy have focused on three areas:1 Increasing the P2 receptor in myocardial cell membrane through transfect the cloning gene of theβ2 receptor, to increase the cardiac response to endogenous and exogenous adrenaline and increase the heart rate; 2 Mutating the gene of Kir2 which encode potassium channels Ik1 to reduce the hyperpolarization current, it would enable the non-pacemaker generate the independent action potential activity as the pacemaker; 3 Transfect the gene of hyperpolarization-activated cyclic nucleotide-gated channel(HCN) which encode the pacemaker current If, it would induce the ventricular cells to beat independently.③Stem cell therapy is to induce stem cells (including the embryonic stem cells, mesenchymal stem cells, etc.) to differentiate into a functional pacemaker and conduction cells, then transplant then into the heart to reconstruction the pacemaker and conduction system.④Bio-pacemaker with the use of genes and stem cells is to load the genes which encode the pacemaker current channel into the stem cells, that is building a genetically modified stem cell.Conclusion Constructing biological pacemaker by gene or stem cells has become an optimal approach to treating the sick sinus syndrome.更多还原