NEURAL CONTROL OF ION CHANNELS AND AUTONOMIC RESPONSE

总体目标是定义发展的性质和时间进程 心肌离子通道功能和自主神经反应性的变化， 以及实现这些变化的机制(S)。这个目标 源自我们的假设(基于此PPG下的先前工作)，即 交感神经支配对心脏表型的营养影响 成熟，从而引起心肌细胞的显著变化 电生理学和药理学。最近在项目D下进行的研究包括 确定了离子电流的重要发展变化 至窦房结冲动起搏(I/Na)、心室起搏(I/f)， 平台(I/Cal)和第三相复极(I/K1，I/To)。然而，这些因素， 神经元和其他的，负责调节这些 洋流是未知的。项目D将决定 这些电流的发展变化以及变化的程度和机制 通过这一点，神经对它们起到了作用。为了达到这一目的，我们使用in 体外方法，允许直接控制的微环境 培养的心肌细胞，包括在功能上 用交感神经元对培养的心肌细胞进行神经支配。我们的第一个目标， 这源于我们最近发现的类I型神经元钠 电流在新生儿窦房结肌细胞中的表达及其意义 该电流对年轻人正常窦性心律的自主控制 心脏，并调查与年龄相关的因素(S) 失去这股电流。我们的第二个目标，源于最近关于 依赖发育和神经支配的激活电压漂移 起搏器电流I/f，包括研究心脏起搏的时间进程 I/f的发育转变，即神经调节的机制 电流(即神经因素)和变化的基础 电流--特别是蛋白激酶C和磷酸化的作用。 我们的第三个目标，来自数据表明神经支配是 可能通过神经释放的NPY来调节I/Cal，是为了确定 神经支配和神经肽Y调节I/Cal的机制 进一步阐明交感神经支配在中枢神经系统中的作用 复极电流I/K1和I/T0的发育成熟。通过 研究心率和复极发生的变化 发展和他们的共鸣调制，我们不仅会提高 我们对正常调节机制的理解 电生理功能，但将提供一个框架来理解 致心律失常的干预措施--在其他项目中进行了研究--对 正常功能。

The overall goal is to define the nature and time course of developmental changes in myocardial ion channel function and autonomic responsiveness, and the mechanism(s) through which these changes are achieved. This goal derives from our hypothesis (based on prior work under this PPG) that are sympathetic innervation exerts a trophic influence on cardiac phenotype maturation, thereby inducing significant changes in myocardial electrophysiology and pharmacology. Recent studies under Project D have identified important developmental changes in ionic currents contributing to sinus node impulse initiation (I/Na), ventricular pacemaking (I/f), the plateau (I/CaL) and phase 3 repolarization (I/K1, I/to). Yet the factors, neuronal and otherwise, that are responsible for regulation of these currents are unknown. Project D will determine the nature of the developmental changes in these currents and extent to which, and mechanism by which, innervation contributes to them. To attain this end we use an in vitro approach that permits the direct control of the micro-environment of myocardial cell in culture, and includes the ability to functionally innervate myocytes in culture with sympathetic neurons. Our first aim, which follows from our recent discovery of a neuronal type I-like Na current in neonatal sinus node myocytes, is to determine the implications of this current for autonomic control of normal sinus rhythm in the young heart, and investigate the factor(s) responsible for the age-dependent loss of this current. Our second aim, which arises from recent data on the developmental and innervation dependent shift in the activation voltage pacemaker current I/f, includes studying the time course of the developmental shift in I/f, the mechanism by which innervation modulates the current (i.e. the neural factor) and the basis of the change in current-in particular the role of protein kinase C and phosphorylation. Our third aim, which derives from data indicating that innervation is likely to regulate I/CaL, via neurally released NPY, is to determine the mechanism by which innervation and NPY modulate I/CaL, as well as to further elucidate the contribution of sympathetic innervation to the developmental maturation of the repolarizing currents I/k1 and I/to. By studying the changes in heart rate and repolarization that occur developmentally and their sympathetic modulation, we will not only improve our understanding of the mechanism that regulate normal electrophysiological function, but will provide a framework for understand how arrhythmogenic interventions-studied in other Projects-impact on normal function.