INTERCELLULAR COUPLING AND PROPAGATION IN CARDIAC TISSUE

我们实验室之前的研究表明，心率- 相关的和间歇性的阻塞过程，例如在文克巴赫期间 房室传导的周期性无法解释 仅基于慢传导，并不兼容 预期的行为形成一个均匀的电耦合电池系统。 此外，有研究表明，细胞间的改变 耦合和其他被动膜的特性可能起着重要的作用 在各种类型心脏传导阻滞过程中的作用 组织。我们的目的是要刻画出 房室结细胞，并观察其增殖特性 兔房室结与心率依赖性房室发育有关 传导障碍和心律失常。此外，我们还将学习制服 和室外膜肌肉的非均匀各向异性，并将 将传播模式与几何分布相关联 细胞间通信。 单电极电流和电压钳位技术在 单个AV节点单元，以及高分辨率光学映射， 电生理记录和免疫组织化学技术，将 用于以下特定目的：1)研究离子 单房室结率相关兴奋模式的机制 手机。2)确定分离株的精确激活序列 兔房室结及其与细胞类型和缝隙的关系 结分布，以及3)表征材料的各向异性传播 心外膜肌与心外膜肌的适用性 连续媒质理论。这些研究应该会提高我们的理解 影响心脏组织传导能力的因素有哪些 电脉冲。结果也应该给出准确和直接的 关于传导块过程的离子基的解答 交替或与文克巴赫周期。

Previous investigations from our laboratory have shown that heart rate- dependent and intermittent block processes, such as during Wenckebach periodicity in atrioventricular (AV) transmission, cannot be explained merely on the basis of slow conduction, and are not compatible with behavior expected form a homogeneous system of electrically coupled cells. In addition, it has been suggested that alterations in cell-to-cell coupling and other passive membrane properties may play a significant role in the development of conduction block processes in all types of cardiac tissue. It is our purpose to characterize the excitability properties of the AV nodal cells, and the propagation characteristics of the isolated rabbit AV node, as they pertain to the development of rate-dependent AV conduction disturbances and arrhythmias. Moreover, we will study uniform and non-uniform anisotropy in ventricular epicardial muscle, and will correlate propagation patterns with the geometrical distribution of intercellular communication. A combination of single-electrode current and voltage clamp techniques in single AV node cells, as well as high resolution optical mapping, electrophysiological recordings and immunohistochemical techniques, will be used toward the following specific aims: 1) To investigate the ionic mechanisms of rate-dependent excitation patterns in the single AV nodal cell. 2) To identify the precise activation sequence of the isolated rabbit atrioventricular node and its correlation with cell type and gap junction distribution, and 3) To characterize anisotropic propagation in ventricular epicardial muscle as it relates to the applicability of the continuous medium theory. These studies should improve our understanding of the factors involved in the ability of the cardiac tissues to conduct electrical impulses. The results should give also precise and direct answers about the ionic bases of conduction block processes with alternation or with Wenckebach periodicity.