ACTIVATION OF CA++ RELEASE IN SKELETAL AND HEART MUSCLE

Ryanodine受体(RyR)是细胞内钙释放的一个家族 频道。在许多脊椎动物中存在两种RyR亚型的共表达 骨骼肌和肌质网钙离子的释放似乎利用 两种异构体。我们不知道双RyR系统是如何运作的，目标是 这个项目的目的是建立这个系统的属性以及它是如何 有助于激活肌肉收缩。此外，我们 将这些肌肉中的钙释放与心肌中的钙进行比较 其中似乎表达了单一的RyR亚型。我们将测试 假设两个RyR串联工作，每个亚型是 专门用于通过与 二氢吡啶受体(DHPR)或钙离子。我们将使用骨骼肌 制备：单独表达每种RyR亚型或同时表达两种RyR亚型 和利用依赖于CaO或不依赖于Ca的SR钙离子的组合 释放装置。在项目的第一阶段，我们将定义 RyR如何被激活以及钙离子的功能特性 电流和与每种制剂相关的肌浆网钙离子释放瞬变。 在这项工作的第二阶段，我们将研究钙离子的作用 确定采用的放行流程中的放行体系组织。 将使用光学和电子显微镜技术来确定 细胞结构和与每个RyR和RyR相关的非RyR蛋白 每种肌质网钙离子释放机制。在这个项目的最后阶段，我们 将建立导致细胞成熟的细胞条件 钙离子释放瞬变。此外，我们还将定义属性 每种异构体介导的钙释放事件。它们之间的相互关系 这些研究的结果将使我们能够定义 双RyR钙离子释放体系的性质、影响因素和条件 确定所使用的发布系统，以及 不同的钙释放系统对胚胎肌肉发育和成熟的影响 肌肉功能。

Ryanodine receptors (RyR) form a family of intracellular Ca2+ release channels. There is co-expression of two RyR isoforms in many vertebrate skeletal muscles and SR Ca2+ release in these muscles appears to utilize both isoforms. We do not know how a two-RyR system operates and the goal of this project is to establish the properties of this system and how it contributes to the activation of muscle contraction. In addition, we will compare Ca2+ release in these muscles with that in cardiac muscle where a single RyR isoform appears to be expressed. We will test the hypothesis that the two RyRs operate in series with each isoform being specialized for activation by interactions with either the dihydropyridine receptor (DHPR) or Ca2+. We will use skeletal muscle preparations: that express each RyR isoform singly or both RyR isoforms in combination, and that utilize CaO-dependent or Ca -independent SR Ca2+ release mechanisms. In the first phase of the project, we will define how each RyR can be activated and the functional properties of the Ca2+ currents and SR Ca2+ release transients associated with each preparation. In the second phase of this work we will investigate the role of Ca2+ release system organization in determining the release process used. Light and electron microscopic techniques will be used to establish the cellular structures and the nonRyR proteins associated with each RyR and each SR Ca2+ release mechanism. In the final phase of this project, we will establish the cellular conditions responsible for the maturation of the Ca2+ release transient. In addition, we will define the properties of the Ca2+ release events mediated by each isoform. Correlations of the results from these studies will permit us to define the functional properties of a two-RyR Ca2+ release system, factors and conditions that determine the release system used, and the contributions made by the different Ca2+ release systems to embryonic muscle development and mature muscle function.