REGULATORY MECHANISMS OF K+ CHANNEL FUNCTION IN HEART

心脏K通道功能的调节机制

• 批准号: 3486138
• 负责人: GABOR SZABO
• 金额: $ 17.82万
• 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 1994-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3486138
• 关键词: Anura; G protein; acetylcholine; 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 an 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 yiel consistent and physiologically relevant conclusions. 3. Efforts will be mad to reconstitute the control of K(m) channels in lipid bilayer membranes by G-protein and receptor, with the ultimate goal of elucidating the structura 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 cel function by extracellular signals.

受体调节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 心脏毒蕈碱受体的变化可能会影响启动和传播 通过打开心脏肌膜中的钾通道来控制心脏跳动。 该项目的长期目标是定量地了解 在分子细节层面，这些调控过程如何运作， 特别强调最近发现的鸟嘌呤的作用 受体效应器偶联中的核苷酸结合蛋白（G 蛋白） 过程。具体来说，毒蕈碱激活内向纠正 将在离体心房肌细胞中研究钾通道 K+(m) 使用这个明确定义的系统应该有助于实现 遵循三个主要目标。 1. 确定关键步骤 参与体内耦合过程及其建模 明确定义的化学动力学过程。全细胞千兆密封记录 将用于跟踪 K+(m) 1 的演变，以响应 以适当的方式操纵激活受体或G蛋白 揭示受体-通道偶联中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 通过将其预测与实验进行比较来完善。 2. 鉴定 体内激活 K+(m) 的 G 蛋白的类型和部分 表征细胞内注射的、高度纯化的效果 心肌细胞离子电流上的 G 蛋白成分。结果 将与在单通道级别上看到的密切相关 切除补丁以确保这两种不同的技术产生 一致且生理相关的结论。 3.努力就会疯狂 重建脂质双层膜中 K(m) 通道的控制 G蛋白和受体，最终目标是阐明其结构 功能监管体系的要求。这个项目很可能 进一步我们对正常和神经激素调节的理解 心脏功能异常。此外，由于 G 蛋白被发现 将受体与几乎所有细胞类型中的效应器偶联，结果是 对于细胞的控制来说必然具有更普遍的意义 通过细胞外信号发挥作用。