DEVELOPMENT OF CARDIAC EXCITATION-CONTRACTION COUPLING

描述：（申请人摘要） 在成人心肌中，去极化激活二氢吡啶（DHP） 横小管（t管）膜中的敏感Ca通道。开放式DHP 钙通道携带少量的钙流进入细胞。这种小的Ca通量充当 触发钙信号，激活肌浆网中的钙通道 （SR）。这项建议旨在研究如何微观属性的 触发Ca信号控制单个SR Ca释放通道的活性， 产生正常心脏功能所必需的局部Ca释放事件。 SR Ca释放通道已被鉴定为ryanodine受体（RyR）。 成年和新生大鼠心室肌RyR单通道的局部钙调控 肌细胞是不同的。成人RyR通道功能明显受 触发Ca信号从并列的DHP敏感Ca的开口上升 渠道新生儿RyR通道功能取决于一个非常不同的集合 形态限制和因素。例如，新生儿细胞没有 t-管，缺乏高度的SR超微结构特化， 成年人了确定控制成人和新生儿的局部钙控制机制 RyR函数将，1）增加有关复杂的 细胞内Ca信号传导系统（即心脏E-C偶联），以及2）提供 新的见解RyR本地钙控制机制的一般。 成人和新生儿RyR的单通道行为将被定义，比较， 并用于生成综合动态马尔可夫模型RyR函数 （目标#1中的平面双层研究）。宏观和微观触发因素 成人和新生儿急性动作电位（AP）产生的信号 测量分离的肌细胞（膜片钳和共聚焦成像研究 目标#2）。单个成人和新生儿RyR通道对这些信号的反应 复杂的触发钙波形将被预测和实验测试 （目标#3中的建模和双层研究）。的时空属性 成人和新生儿细胞中诱发和自发的细胞内Ca信号将 定义并与单个成人和新生儿的局部钙控制相关 RyR通道（建模和共聚焦成像研究，目标#4）。

DESCRIPTION: (Applicant's Abstract) In adult cardiac muscle, depolarization activates dihydropyridine (DHP) sensitive Ca channels in the transverse tubule (t-tube) membrane. The open DHP Ca channel carries a small Ca flux into the cell. This small Ca flux acts as a trigger Ca signal that activates Ca channels in the sarcoplasmic reticulum (SR). This proposal seeks to examine how the microscopic attributes of the trigger Ca signal govern the activity of single SR Ca release channels and thus generate the local Ca release events essential to normal cardiac function. The SR Ca release channel has been identified as the ryanodine receptor (RyR). Local Ca control of single RyR channels in adult and neonate rat ventricular myocytes is different. Adult RyR channel function is clearly governed by trigger Ca signals rising from the opening of juxtaposed DHP sensitive Ca channels. Neonate RyR channel function depends on a very different set morphological constraints and factors. For example, neonate cells have no t-tubes and lacks the high degree of SR ultrastructural specialization seen in adult. Defining the local Ca control mechanisms that govern adult and neonate RyR function will, 1) increase knowledge concerning development of an intricate intracellular Ca signaling system (i.e. cardiac E-C coupling) and, 2) provide new insights into RyR local Ca control mechanisms in general. The single channel behavior of adult and neonate RyR will be defined, compared, and used to generate comprehensive dynamic Markovian models RyR function (planar bilayer studies in Aim #1). The macro- and microscopic trigger Ca signals generated by the action potential (AP) in adult and neonate acutely dissociated myocytes will be measured (patch-clamp & confocal imaging studies in Aim #2). The response of single adult and neonate RyR channels to these complex trigger Ca waveforms will be predicted and experimentally tested (modeling & bilayer studies in Aim #3). The spatio-temporal attributes of evoked and spontaneous intracellular Ca signals in adult and neonate cells will be defined and correlated to the local Ca control of single adult and neonate RyR channels (modeling & confocal imaging studies, Aim #4).