CELLULAR MAGNESIUM ION HOMEOSTASIS IN THE MYOCARDIUM

心肌细胞镁离子稳态

• 批准号: 5213233
• 负责人: ANTONIO SCARPA
• 金额: --
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/5213233
• 关键词: cyclic AMP; heart cell; homeostasis; hormone regulation /control mechanism; intracellular transport; ion transport; laboratory rat; magnesium; mitochondrial membrane; muscle cells; myocardium; organelles; oxidative phosphorylation; sarcolemma; sarcoplasmic reticulum; tissue /cell culture

Studies conducted during the previous funding period and by other laboratories indicate that specific hormonal stimulation or intracellular signals rapidly mobilize large amounts of Mg2+ from myocytes (or other cells) to the extracellular space, and vice versa. On the other hand, the general understanding, supported by experimental data, assumes that cytosolic free Mg2+ is held relatively constant at a millimolar- submillimolar concentration. Hence, the main hypothesis of the research of this Component Project is to demonstrate that hormonal stimulation of myocytes induces redistribution of Mg2+ between intracellular organelles and the extracellular space, leaving cytosolic Mg2+ virtually unchanged. Key to athe hypothesis is the demonstration that specific intracellular signals induce large fluxes of Mg2+ across organelles such as mitochondria, sarcoplasmic reticulum and the cytosol, and that these fluxes are coupled with the activation of powerful sarcolemma Mg2+ transporter(s). The five specific aims proposed will define the operation and regulation of various mechanisms used by the myocardial cell to translocate Mg2+ across the sarcolemma, sarcoplasmic reticulum and mitochondria. Some of the aims proposed a broad and systemic investigation, whereas others are very specific. One example of the latter is the investigation of the cAMP binding to two isozymes of the adenine nucleotide translocase and the resulting Mg-ATP transport from mitochondrial when cAMP is bound. A large variety of models (anesthetized animals, perfused hearts, myocytes, other isolated cells, permeabilized cells, isolated organelles, purified proteins, liposomes) and experimental approaches (31P NMR, Electron Probe Microanalysis, cell imaging, isotopic, potentiometric techniques) will be used to confirm or to integrate the acquired knowledge on myocyte Mg2+ homeostasis. Additional integration is proposed in Aim 1 by information derived from experiments using anesthetized animals. Using this model, the overall results and consequences of Mg2+ redistribution between tissues and plasma will be investigated. Finally, in collaboration with other investigators of this Program Project, the results of Mg2+ redistribution within the myocyte and the changes in organelle Mg2+ will be correlated with the function of the organelles or myocytes in terms of ATP synthesis and utilization, and regulation of ion gradients.

在上一个资金期间进行的研究以及其他 实验室表明特定的激素刺激或细胞内 信号从肌细胞迅速动员大量的MG2+（或其他 细胞）到细胞外空间，反之亦然。 另一方面， 由实验数据支持的一般理解假定 在毫米 - 亚摩尔峰值浓度。 因此，该组件项目研究的主要假设是 证明肌细胞的激素刺激会诱导重新分布 细胞内细胞器和细胞外空间之间的MG2+，离开 胞质MG2+几乎没有变化。 Athe假设的关键是 证明特定细胞内信号会诱导大型通量 MG2+跨线粒体，肌质网和 细胞质，并且这些通量与强大的激活相结合 Sarcolemma MG2+转运蛋白。 提出的五个具体目标将定义 心肌细胞使用的各种机制将MG2+转移到跨越的MG2+ 肌膜，肌质网和线粒体。 一些目的 提出了广泛而系统的调查，而其他人非常 具体的。 后者的一个例子是对营地的调查 与腺嘌呤核苷酸易位酶的两个同工酶结合和 cAMP被绑定时，导致MG-ATP从线粒体运输。 多种模型（麻醉动物，灌注心脏，心肌细胞， 其他分离的细胞，透化细胞，分离的细胞器，纯化 蛋白质，脂质体）和实验方法（31p NMR，电子探针 微分析，细胞成像，同位素，电位计量技术）将是 用于确认或整合在Myocyte MG2+上获得的知识 稳态。 AIM 1中提出了其他集成 使用麻醉动物进行实验。 使用此模型，总体 组织和等离子体之间MG2+重新分布的结果和后果 将被调查。 最后，与该计划项目的其他研究人员合作， MG2+重新分布的肌细胞和变化的变化 细胞器MG2+将与细胞器的功能相关 在ATP合成和利用方面的心肌细胞以及离子的调节 梯度。