Reentrant Activity in Cultured Cardiac Cell Monolayers

折返机制在许多类型的心律失常中起主要作用。功能性折返，在 螺旋波的形式，是许多心动过速以及纤颤的基础，但螺旋波的动力学特性 波的稳定性和破碎仍然没有得到很好的表征。我们实验室以前的工作已经证明， 在培养的新生儿肺动脉单层细胞中，可以诱导并系统地研究持续的螺旋波活动 大鼠心室肌细胞这项工作的重点将是螺旋波的性质，特别是如何他们 受到组织异质性岛的影响，包括改变的离子通道表达，间隙连接， 偶联和异位病灶。组织工程方法将被用来允许系统评价 在特定位置的不同类型的异质性。 我们建议使用电压和钙敏感的染料和多站点光学映射来跟踪 心肌细胞单层的折返活动。我们将检验假设，（1）细胞的区域差异 膜的特性可以锚折返波并改变周期长度;（2）组织中的异质性 微结构导致不连续的传播并放大解剖障碍物的锚定效应， (3)在再入过程中，阻滞线起源于微不均匀性，它们的长度由 兴奋性，波长和组织各向异性，（4）改变离子通道表达的岛屿可能足以 引发螺旋波分裂，特别是在细胞-细胞耦合减少的条件下，和（5）触发 活动和后去极化可以引起螺旋波分裂，但需要临界质量和临界 偶合器.这些目标利用培养的细胞单层作为一种良好控制的、多功能的 和定量实验模型，用于临床重要的折返性心律失常的基础研究。

Reentrant mechanisms play a primary role in many types of cardiac arrhythmias. Functional reentry, in the form of spiral waves, underlies many tachycardias as well as fibrillation, but the dynamic properties of spiral wave stability and breakup are still not well characterized. Previous work from our lab has demonstrated that sustained spiral wave activity can be induced and systematically studied in monolayers of cultured neonatal rat ventricular cells. The focus of this work will be on the properties of spiral waves, and particularly how they are influenced by islands of tissue heterogeneities that include altered ion channel expression, gap junctional coupling, and ectopic foci. Tissue engineering approaches will be utilized to permit a systematic evaluation of different types of heterogeneities at specified locations. We propose to use voltage- and calcium-sensitive dyes and multi-site optical mapping to track the reentrant activity in cardiac cell monolayers. We will test the hypotheses, (1) Regional differences in cellular membrane properties can anchor reentrant waves and alter cycle length, (2) Heterogeneities in tissue microstructure result in discontinous propagation and amplify the anchoring effects of anatomical obstacles, (3) Lines of block during reentry originate from microheterogeneities, and their length is modulated by excitability, wavelength and tissue anisotropy, (4) Islands of altered ion channel expression may suffice to initiate spiral wave breakup, particularly under conditions of reduced cell-cell coupling, and (5) Triggered activity and afterdepolarizations can cause spiral wave breakup but require critical mass and critical coupling. These aims exploit the properties of the cultured cell monolayer as a well-controlled, versatile and quantitative experimental model for basic studies of clinically important, reentry-based arrhythmias.