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。功能性再入，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 波浪稳定性和解体仍未得到很好的描述。我们实验室以前的工作已经证明 在培养的新生儿单层中可以诱导和系统地研究持续螺旋波活动 大鼠心肌细胞。这项工作的重点将是螺旋波的性质，特别是如何 受到组织异质性孤岛的影响，包括离子通道表达的改变，缝隙连接 耦合和异位病灶。将利用组织工程学方法来进行系统的评估 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染料和多点光学标测来追踪 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 膜特性可以锚定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的锚定效应， (3)再入过程中的块状线起源于微非均质，其长度受 兴奋性、波长和组织各向异性，(4)离子通道表达改变的孤岛可能足以 启动螺旋波分解，特别是在细胞-细胞耦合减少的条件下，以及(5)触发 活动和后去极化可导致螺旋波破裂，但需要临界质量和临界 耦合。这些目的是利用培养的细胞单层的特性作为一种控制良好的、多功能的 以及用于临床上重要的、基于折返性心律失常的基础研究的定量实验模型。

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.