REENTRANT ACTIVITY IN CULTURED CARDIAC CELL MONOLAYERS

重入机制在许多类型的心律失常中起主要作用，包括心房、心室和房室结的心动过速和扑动。再入可能涉及解剖途径，也可能涉及功能性，主要有圆形、8字形、各向异性和螺旋波变异。本研究的主要目的是在良好控制的实验条件下，建立一个简单、可重复的培养细胞模型，用于心脏再入解剖和功能的研究。我们建议使用电压敏感染料和高分辨率光学成像来监测新生大鼠心脏细胞单层的重入活性。一个详细的计算模型将通过从动作电位和细胞内钙测量得出的实验数据进行验证，以及它们在该实验模型中的恢复和速率依赖行为。计算模型将用于确定离子电流和负责再入行为的生物物理机制。新的微加工和表面化学方法也将用于开发有图案的底物，以指导细胞在单层中的生长。本研究中提出的实验和计算相结合的方法将允许对组织行为进行详细的定量分析和解剖，直至细胞水平。我们将：1)建立一个基于实验的新生大鼠心脏细胞单层的生物物理模型；2)表征培养的新生大鼠心脏细胞融合单层的再入特性；3)确定再入回路核心的电生理特性和作用。将讨论临界质量、可激隙和导圆与螺旋波再入的问题。这些目标将使培养的细胞单层成为一种控制良好的、通用的和定量的实验模型，用于再入心律失常的基础研究。该模型系统的简单性和灵活性比现有的再入性心律失常组织模型提供了许多优势。此外，细胞培养非常适合于涉及药理学、遗传学和分子操作的研究。

Reentrant mechanisms play a primary role in many types of arrhythmias, including tachycardia and flutter in the atria, ventricles, and atrioventricular node. Reentry may involve anatomical pathways, or it may be functional, with leading circle, figure-eight, anisotropic, and spiral wave variants. The primary goal of this research is to establish a simple and reproducible cultured cell model for the study of anatomical and functional cardiac reentry under well-controlled experimental conditions. We propose to use voltage-sensitive dyes and high- resolution optical mapping to monitor reentrant activity in monolayers of neonatal rat heart cells. A detailed computational model will be verified against experimental data drawn from action potential and intracellular calcium measurements, and their restitution and rate-dependent behavior in this experimental model. The computational model will be used to identify the ionic currents and biophysical mechanisms responsible for reentry behavior. New microfabrication and surface chemical approaches will also be used to develop patterned substrates that direct the growth of cells in the monolayers. The combined experimental and computational approach that is proposed in this study will permit a detailed quantitative analysis and dissection of tissue behavior down to the cellular level. We will, 1) formulate an experimentally-based, biophysical model of the neonatal rat cardiac cell monolayer 2) characterize reentry in confluent monolayers of cultured neonatal rat heart cells, and 3) determine the electrophysiological properties and role of the core of the reentrant circuits. Issues of critical mass, excitable gap, and leading circle vs. spiral wave reentry will be addressed. These aims will establish the cultured cell monolayer as a well-controlled, versatile and quantitative experimental model for basic studies of reentry- based arrhythmias. The simplicity and flexibility of this model system provides numerous advantages over existing tissue models of reentrant arrhythmia. Moreover, the cell culture is well suited for studies involving pharmacological, genetic and molecular manipulation.