REGULATORY MECHANISMS OF K+ CHANNEL FUNCTION IN HEART

心脏K通道功能的调节机制

• 批准号: 2445146
• 负责人: GABOR SZABO
• 金额: $ 25.08万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-09-30 至 1999-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2445146
• 关键词: Anura; G protein; acetylcholine; alternatives to animals in research; computer simulation; guanine nucleotides; guinea pigs; heart cell; heart function; heart rate; hormone regulation /control mechanism; mathematical model; membrane lipids; membrane model; membrane permeability; membrane potentials; membrane proteins; membrane reconstitution /synthesis; muscarinic receptor; muscle cells; neural information processing; potassium channel; protein structure

Receptor-modulated ion channels play a primary role in the neuroendocrine regulation of cardiac function. Thus, for example, cholinergic activation of cardiac muscarinic receptors may affect the initiation and propagation of the heart beat by opening potassium channels in the cardiac sarcolemma. The long-range objective of this project is to understand quantitatively and at the level of molecular detail, how these regulatory processes operate, with particular emphasis on the recently discovered role of guanine nucleotide binding proteins (G-proteins) in the receptor effector coupling process. Specifically, muscarinic activation of the inwardly rectifying potassium channel K+(m) will be studied in isolated cardiac atrial myocytes. Use of this well defined system should facilitate the attainment of the following three primary objectives. 1. Identification of the critical steps involved in the coupling process in vivo and its modeling in terms of clearly defined chemical kinetic processes. Whole-cell gigaseal recording will be used to follow the evolution of K+(m) 1. in response to manipulations activating receptor or G-protein in a manner appropriate for revealing the specific kinetic steps involved in receptor-channel coupling. The results will be used to construct a mathematical model to be tested and refined by comparing its predictions with experiment. 2. Identification of the type and moiety of G-protein(s) that activate K+(m) in vivo by characterizing the effects of intracellularly injected, highly purifiid G-protein components on the ionic currents of cardiac myocytes. The results will be carefully related to those seen at the single-channel level with excised patches in order to insure that these two different techniques yield consistent and physiologically relevant conclusions. 3. Efforts will be made to reconstitute the control of K(m) channels in lipid bilayer membranes by G-protein and receptor, with the ultimate goal of elucidating the structural requirements for a functional regulatory system. This project is likely to further our understanding of the neurohormonal regulation of normal and abnormal cardiac function. Moreover, since G-proteins have been found to couple receptors to effectors in virtually all cell types, the results are bound to be of more general significance with respect to the control of cell function by extracellular signals.

受体调节的离子通道在神经内分泌中起主要作用 心脏功能的调节。 因此，例如，胆碱能激活 心脏毒蕈碱受体可能会影响开始和传播 通过在心脏肌膜中打开钾通道来跳动。 该项目的远程目标是定量理解 在分子细节的层面上，这些调节过程如何 操作，特别强调了最近发现的作用 受体效应子中的鸟嘌呤核苷酸结合蛋白（G蛋白） 耦合过程。 具体而言，内部的毒蕈碱激活 将在孤立的心脏中研究整流的钾通道K+（M） 心肌细胞。 使用该定义良好的系统应有助于实现 遵循三个主要目标。 1。识别关键 体内耦合过程及其建模涉及的步骤 明确定义的化学动力学过程。 全细胞Gigaseal录制 将用于遵循K+（M）1的演变。 以适合的方式进行操作激活受体或G蛋白 揭示了受体通道耦合所涉及的特定动力学步骤。 结果将用于构建要测试的数学模型，并 通过将其预测与实验进行比较。 2。识别 通过体内激活K+（M）的G蛋白的类型和部分 表征细胞内注射，高度净化的影响 心肌细胞离子电流上的G蛋白成分。 这 结果将与单渠道级别所看到的结果仔细相关 使用切除的补丁，以确保这两种不同的技术 产生一致且与生理相关的结论。 3。努力 将建立脂质双层中K（M）通道的控制 G蛋白和受体的膜，其最终目标是阐明 功能监管系统的结构要求。 这 项目可能会进一步了解我们对神经激素的理解 调节正常和异常心脏功能。 而且，从那以后 已经发现G蛋白是将受体与实际上的效应子相对的 所有细胞类型，结果必然具有更普遍的意义 关于通过细胞外信号控制细胞功能。