DEVELOPMENT OF CARDIAC EXCITATION-CONTRACTION COUPLING

描述：(申请人摘要) 在成人心肌，去极化激活二氢吡啶(DHP) 横管(T管)膜上的敏感钙通道。开放的DHP 钙离子通道携带少量的钙离子进入细胞。这种小的钙通量起到了 触发钙信号激活肌浆网钙通道 (Sr)这项提议试图研究人类的微观属性是如何 触发钙信号调控单个肌质网钙释放通道的活性，因此 产生对正常心脏功能至关重要的局部钙释放事件。 肌浆网钙释放通道被认为是兰尼定受体(RyR)。 成年和新生大鼠左心室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 DHP并列敏感钙通道开口触发钙信号上升 频道。新生儿RyR通道功能依赖于一套非常不同的设置 形态约束和因素。例如，新生细胞没有 T管，缺乏SR超微结构高度的特化 成年人。确定管理成人和新生儿的局部钙控制机制 RyR功能将，1)增加关于复杂的 细胞内钙信号系统(即心脏E-C偶联)和，2)提供 总体上对RyR局部钙调控机制的新见解。 成年和新生儿RyR的单通道行为将被定义、比较 并用来生成综合的动态马尔可夫模型RyR函数 (目标1中的平面双层研究)。宏观和微观触发案例 成人和新生儿急性动作电位(AP)产生的信号 将测量分离的心肌细胞(膜片钳和共聚焦成像研究 在目标2中)。单个成人和新生儿RyR通道对这些信号的反应 将预测复杂的触发钙波形并进行实验测试 (目标3中的建模和双层研究)。地球的时空属性 在成人和新生细胞中诱发的和自发的细胞内钙信号将 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).