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，包括心房、心室和房室结中的心动过速和扑动。 折返可能涉及解剖路径，也可能是功能性的，具有前导圆、8字形、各向异性和螺旋波变体。 本研究的主要目的是建立一个简单的和可重复的培养细胞模型，用于在良好控制的实验条件下研究解剖和功能性心脏折返。 我们建议使用电压敏感染料和高分辨率光学映射来监测新生大鼠心肌细胞单层的折返活性。 详细的计算模型将根据从动作电位和细胞内钙测量得出的实验数据进行验证，以及在该实验模型中它们的恢复和速率依赖性行为。 计算模型将用于确定离子电流和生物物理机制负责再入行为。 新的微加工和表面化学方法也将用于开发图案化的基底，指导细胞在单层中的生长。在这项研究中提出的实验和计算相结合的方法将允许详细的定量分析和解剖的组织行为下降到细胞水平。 我们将，1）制定一个实验为基础的，生物物理模型的新生大鼠心肌细胞单层2）表征折返在汇合单层培养的新生大鼠心脏细胞，和3）确定的电生理特性和作用的核心折返电路。临界质量，可激发间隙，和领先的圆与螺旋波再入的问题将得到解决。 这些目标将建立一个良好的控制，多功能和定量的实验模型，为基础研究折返性心律失常的细胞单层培养。 该模型系统的简单性和灵活性提供了许多优于现有折返性心律失常组织模型的优点。 此外，细胞培养非常适合涉及药理学、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.