INTERCELLULAR COUPLING AND PROPAGATION IN CARDIAC TISSUE

我们实验室以前的研究表明，心率- 依赖性和间歇性阻滞过程，如文氏过程 房室（AV）传输的周期性，无法解释 仅仅基于缓慢传导，并且不兼容于 预期的行为形成电耦合电池的均匀系统。 此外，有人认为，细胞间的变化， 耦合和其他被动膜特性可能起重要作用 在所有类型的心脏传导阻滞过程中， 组织. 这是我们的目的，表征的兴奋性特性， 房室结细胞，和传播特性的分离 兔房室结，因为它们与频率依赖性房室结的发育有关 传导障碍和心律失常。此外，我们将研究制服 以及心室心外膜肌的非均匀各向异性， 将传播模式与 细胞间通讯 单电极电流钳和电压钳技术相结合， 单个房室结细胞，以及高分辨率光学标测， 电生理记录和免疫组织化学技术，将 用于以下具体目的：1）研究离子 单个房室结频率依赖性兴奋模式的机制 cell. 2)为了确定分离的病毒的精确激活序列， 家兔房室结及其与细胞类型和间隙的关系 结分布，以及3）为了表征在 心室心外膜肌，因为它涉及到的适用性， 连续介质理论 这些研究应该能增进我们对 参与心脏组织传导能力的因素 电脉冲 结果也应该精确和直接 关于传导阻滞过程的离子碱的答案， 交替或具有文氏周期性。

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.