CALCIUM MOVEMENTS IN EXCITATION CONTRACTION COUPLING

动作电位向肌肉收缩的转导 耦合)是细胞膜之间快速通信的一个例子 事件和代谢状态。正如在许多系统中一样，中央信使 这种偶联是钙，它在肌肉中从 肌浆网(SR)激活收缩蛋白。这个 SR的释放通道受控于 血浆和T管膜。这个项目的长期目标是 理解这种控制。自上一次续期以来， 两个关键分子的身份，T的电压传感器 膜和SR的释放通道已为人所知。中环 欧共体耦合问题--以及本提案的问题--现在可以表述为 了解二氢吡啶受体之间的相互作用 DHPr分子(电压传感器)与Ryanodine受体 (发布频道)。对这个问题的简约主义方法将是 使用，包括对整个系统及其部件的研究。 整个系统的测量将包括膜内 电荷运动(电压传感器的一种表现形式)与钙释放 单个骨骼肌细胞中的流量。一种新的电压钳位技术将 改进以前的测量结果。了解前向传输将 要求说明新发现的反向传播：CA 释放反馈到电压传感器上。电荷运动，钙释放， 并将传播机制统一在一个全面的模式中 EC联结。在这个框架中，将有可能测试 从数量上讲，有两种可能的前向传输机制： 机械，通过DHPr和RyR之间的直接或间接接触，或 化学物质，通过可扩散的发射器。 要分别研究系统的各个部分，有两个准备工作 将使用：在双层中使用DHPR和RYR的单通道记录 以及心肌细胞钙通道门控电流的测量。一个 对系统及其部件的性能进行比较将确定 依赖于交互的属性，并帮助决定是否 变速器是机械式的。有希望的前期工作，在其中 在双层中展示了相互作用，通过将组件 在一起，将继续和延伸。 E-C耦合的分子机制从根本上说是 类似于膜生物物理的其他现象，以及关键分子 玩家是在其他地方发现的接近的通道蛋白亚型。因此，在 除了本研究应具有的强制性相关性之外 为了理解肌肉功能障碍和治疗，在 EC耦合应该对CNS的研究产生更广泛的影响 问题，心脏和平滑的肌肉。

The transduction of action potential to muscle contraction (EC coupling) is an example of fast communication between cell membrane events and metabolic state. As in many systems, the central messenger of this coupling is calcium, which in muscle is released from the Sarcoplasmic Reticulum (SR) to activate contractile proteins. The release channels of the SR are controlled by changes in potential at the plasma and T-tubular membrane. The long term goal of this project is to understand this control. Since the last renewal of this grant, the identity of two key molecular players, the voltage sensor of the T membrane and the release channel of the SR, became known. The central problem of EC coupling -and of this proposal- can now be formulated as understanding the interaction between the dihydropyridine receptor or DHPr molecule (voltage sensor) and the ryanodine receptor or R Yr (release channel). A reductionist approach to this question will be used, consisting of studies of the complete system and its parts. Measurements in the complete system will include intramembrane charge movement (a manifestation of the voltage sensor) and Ca release flux in single skeletal muscle cells. A new voltage clamp technique will improve previous measurements. Understanding forward transmission will require the elucidation of a newly found backward transmission: Ca release feeds back on the voltage sensor. Charge movement, Ca release, and mechanisms of transmission will be unified in a comprehensive model of EC coupling. In this framework it will be possible to test quantitatively two possible mechanisms of forward transmission: mechanical, by direct or indirect contact between DHPr and RYr, or chemical, via a diffusible transmitter. To study the parts of the system separately, two preparations will be used: single channel recording with DHPrs and RYrs in bilayers and measurement of Ca channel gating currents in heart cells. A comparison of the properties of the system and its parts will identify properties that depend on the interaction, and help decide whether the transmission is mechanical. Promising preliminary work, in which an interaction was demonstrated in bilayers by putting the components together, will be continued and extended. The molecular mechanisms in E-C coupling are fundamentally similar to other phenomena of membrane biophysics, and the key molecular players are close isoforms of channel proteins found elsewhere. Thus, in addition to the obligatory relevance that the present studies should have to the understanding of muscle dysfunction and therapeutics, findings in Ec coupling should have a more general impact, on research of CNS problems, heart and smooth muscle.