TRANSMEMBRANE POTENTIAL MAPPING OF DEFIBRILLATION

这项研究将获得关于电的影响的基础知识 除颤引起的心脏震荡需要了解 除颤。除颤被认为有三个步骤：1) 电击改变了电击脉冲期间的跨膜电压。2) 跨膜电压的变化改变跨膜电压依赖关系 刺激细胞或延长动作电位的离子通道 脉冲后的复极化。3)兴奋或延长 复极会产生除颤。这些步骤的机制不是 为人所知。 该项目将使用跨膜电压敏感染料荧光和 一种激光扫描系统，可研究孤立动脉上多达127个位置 灌流的兔心。不同时间跨膜电压分布 电击脉冲，刺激或延长的复极后 脉搏和激活模式的变化以及产生所需的阻断 除颤将被确定。动作电位的最大dv/dt 用微电极和钠通道调制器测量， 河豚毒素和高钾，将用于研究跨膜 单相电压依赖性快内向钠通道恢复 和双相电击。快速内向钠通道的重要性 冲击造成的长期复极化的恢复将是 下定决心。药理钠、钙或钾的影响 通道阻断，出现在一些接受电击的患者身上。在……上面 长时间的复极化将被确定。钙敏感染料 将用激光扫描系统测量荧光，以研究 缺血、纤颤和跨膜电压在脑缺血过程中的作用 产生升高的细胞内钙的电击。重要的一点是 自发性纤颤诱发的细胞内钙升高， 将确定纤颤的维护和除颤。这个 项目将产生推进所需的洞察力 了解除颤的细胞基础。

This research will obtain fundamental knowledge of effects of electrical defibrillation shocks in the heart that is needed to understand defibrillation. Defibrillation is thought to occur in three steps: 1) The shock changes transmembrane voltages during the shock pulse. 2) The changes in transmembrane voltages alter transmembrane voltage-dependent ion channels which excite the cells or prolong action potential repolarization after the pulse. 3) The excitation or prolonged repolarization produces defibrillation. Mechanisms for the steps are not known. This project will use transmembrane voltage-sensitive dye fluorescence and a laser scanner system to study up to 127 locations on isolated arterially perfused rabbit hearts. The distributions of transmembrane voltages during the shock pulse, the excitation or prolonged repolarization after the pulse and the changes in activation patterns and block required to produce defibrillation will be determined. The maximum dV/dt of action potentials measured with microelectrodes and the sodium channel modulators, tetrodotoxin and high potassium, will be used to study transmembrane voltage-dependent fast inward sodium channel recovery during monophasic and biphasic shocks. The importance of the fast inward sodium channel recovery for the prolonged repolarization produced by the shocks will be determined. The impacts of pharmacological sodium, calcium or potassium channel blockade, present in some patients who receive shocks. on prolonged repolarization will be determined. Calcium-sensitive dye fluorescence will be measured with the laser scanner system to study the roles of ischemia, fibrillation and the transmembrane voltages during shocks in producing elevated intracellular calcium. The importance of the elevated intracellular calcium for spontaneous fibrillation induction, fibrillation maintenance and defibrillation will be determined. The project will yield insights that are necessary in order to advance understanding of cellular bases of defibrillation.