ION CHANNEL FUNCTION IN CELLS FROM INFARCTED HEARTS

本报告中建议的研究的总体长期目标 应用是为了识别和理解离子机制， 是跨膜电位异常的基础， 存活于心外膜边缘的心外膜下心室细胞 梗塞心脏的区域。 有人建议， 这些电生理异常可能导致严重的 已知在梗死后发生的室性心律失常。 因此通过 更清楚地界定和理解这些机制， 电生理变化，我们将提供可能导致 开发有效的治疗干预措施， 临床设置。 我们将使用分解单个 将这些细胞与心脏的心外膜边缘区分离， 心肌梗塞 然后，通过使用各种电生理 技术，我们可以确定潜在的基础，为电气 异常 对于这一建议，我们重点澄清了 一些离子电流的异常已知是不可或缺的， 正常细胞电生理（iNa、iCaL、iCl（Ca）、iK）。 此外，本发明还提供了一种方法， 当识别出细胞中正常离子通道的功能障碍时， 梗塞的心脏，我们将继续在定义这些敏感性 某些药物的离子通道改变，例如I类 药物、肾上腺素能胺、III类抗肿瘤药物等。 最后，我们将定量和比较静息Cai以及振幅 从心外膜边缘区分散的细胞中的Cai瞬变， 对照细胞。 特别是，我们将集中于放宽利率 药物干预期间的CAI瞬变（例如β肾上腺素能 刺激）和特定起搏协议。 对于这些实验，我们 也将联合收割机与全电池电压钳位技术相结合 使用Fura-2荧光显微镜测量Cai瞬变。 在 这样我们就可以检验正常心脏组织中的改变 功能以及离子通道功能， 蔡的变化。

The overall long term objectives of the studies proposed in this application are to identify and to understand the ionic mechanisms that underlie the abnormalities in the transmember potentials of the subepicardial ventricular cells that survive in the epicardial border zone of the infarcted heart. It has been suggested that one or more of these electrophysiologic abnormalities may lead to the serious ventricular arrhythmias known to occur after infarction. Therefore, by more clearly defining and understanding the mechanisms for these electrophysiologic changes, we will provide information that may lead to the development of effective therapeutic interventions needed in this clinical setting. We will use the technique of disaggregated single cells to separate these cells from the epicardial border zone of the infarcted myocardium. Then, by using a variety of electrophysiologic techniques we can determine the underlying basis for the electrical abnormalities. For this proposal, we have focused on clarifying the abnormalities of some of the ionic currents known to be integral to normal cell electrophysiology (iNa, iCaL, iCl(Ca), iK). In addition, upon recognition of the dysfunction of a normal ion channel in cells from the infarcted heart, we will proceed in defining the sensitivity of these altered ion channels to certain pharmacologic agents, e.g. Class I agents, adrenergic amines, Class III antiarrhythmic agents, etc. Finally, we will quantitate and compare resting Cai as well as amplitude of Cai transients in cells dispersed from the epicardial border zone with control cells. In particular, we will focus on rates of relaxation of Cai transients during pharmacologic interventions (e.g. beta adrenergic stimulation) and specific pacing protocols. For these experiments, we will also combine whole cell voltage clamp techniques with the measurement of Cai transients using fura-2 fluorescence microscopy. In this way we can test the hypothesis that alterations in normal cardiac function as well as ion channel function result from or result in measured changes in Cai.