ACTIVATION OF CA++ RELEASE IN SKELETAL AND HEART MUSCLE

Ryanodine受体（RyR）形成细胞内Ca 2+释放家族 渠道 在许多脊椎动物中存在两种RyR亚型的共表达 骨骼肌和SR Ca2+释放在这些肌肉似乎利用 两种异构体。 我们不知道两个RyR系统是如何运作的， 这个项目的目的是建立这个系统的属性，以及它如何 有助于激活肌肉收缩。 另外我们 我将比较这些肌肉和心肌中Ca2+的释放 其中似乎表达单个RyR同种型。 我们将测试 假设两个RyR串联运作，每个同种型是 专门用于通过与 二氢吡啶受体（DHPR）或Ca 2+。 我们将使用骨骼肌 制备物：单独表达每种RyR亚型或表达两种RyR亚型 并利用CaO依赖性或Ca非依赖性SR Ca 2 + 释放机制。 在项目的第一阶段，我们将定义 每个RyR如何被激活以及Ca2+的功能特性 电流和SR Ca2+释放瞬变与每种制备相关。 在这项工作的第二阶段，我们将研究Ca 2+的作用， 发布系统组织在确定使用的发布过程。 光镜和电子显微镜技术将用于建立 细胞结构和与每个RyR相关的非RyR蛋白， 每个SR Ca2+释放机制。 在这个项目的最后阶段，我们 将建立负责成熟的细胞条件， Ca2+释放瞬变。 此外，我们还将定义 由每种亚型介导的Ca2+释放事件。 的相关性 这些研究的结果将使我们能够定义功能 两个RyR Ca2+释放系统的性质， 确定所使用的发布系统，以及 不同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.