IN VIVO NMR STUDIES OF CELLULAR MAGNESIUM

一般认为，胞质离子在细胞内起着重要的作用。 在调节细胞代谢中的作用， 离子稳态紊乱， 环境化学物质或重金属可能是一个重要因素 解释观察到的毒性。 尽管对 金属离子的调节作用主要集中在 胞浆钙离子，越来越多的人认识到 其中胞质镁离子在生理和 病理生理过程。 据报道，镁离子 调节许多细胞活性，如腺苷酸环化酶，钙离子通道， 从心脏的肌浆网和血浆中释放 膜形成通道。 对细胞质中 镁作为细胞功能的急性或慢性调节剂， 由于缺乏适当的监测方法而受到阻碍。 我们已经开发了一系列细胞内指标， 在生理条件下具有解离常数的镁 范围，和其他细胞离子的解离常数， 远高于生理浓度 一个系列的 细胞内指示剂含有氟元素， 使用氟-19核磁共振检测。 的 得到的螯合剂系列：4-氟、5-氟和4-甲基- 5-氟邻氨基苯酚-N，N，O-三乙酸酯（APTRA）已被 表征了 第二种方法将荧光团 由Tsien开发的APTRA结构， 指标 指示剂2-（2-（5-羧基）恶唑）-5-羟基-6- 已对氨基苯并呋喃-N，N，O-三乙酸酯（FURAPTRA）进行了评价， 测定Ca和Mg离子的解离常数， 为53 μ M（远高于生理水平）和1.5 mM（接近 生理水平）。

It is generally recognized that cytosolic ions play a significant role in the regulation of cellular metabolism, and that disturbances in ionic homeostases resulting from exposure to environmental chemicals or heavy metals may be a significant factor in explaining observed toxicity. Although interest in the regulatory role of metals ions has chiefly centered around cytosolic calcium, there is an increasing appreciation of the role which cytosolic magnesium ions play in physiological and pathophysiological processes. Magnesium ions are reported to modulate many cell activities such as adenylate cyclase, calcium release from the sarcoplasmic reticulum in heart, and the plasma membrane a channel. An evaluation of the role of cytosolic magnesium as an acute or chronic regulator of cell function has been hampered by the lack of suitable methods for monitoring it. We have developed a series of intracellular indicators for magnesium which have dissociation constants in the physiological range, and dissociation constants for other cellular ions which are well above the physiological concentrations. One series of intracellular indicators contains the element fluorine and can be detected using fluorine-19 nuclear magnetic resonance. The resulting series of chelators: 4-fluoro, 5-fluoro, and 4-methyl- 5-fluoro o-aminophenol-N,N,O-triacetate (APTRA) have been characterized. A second approach combines the fluorophores developed by Tsien with the APTRA structure to yield fluorescent indicators. The indicator 2-(2-(5-carboxy)oxazole)-5-hydroxy-6- aminobenzofuran-N,N,O-triacetate (FURAPTRA) has been evaluated and the dissociation constants for Ca and Mg ions were determined to be 53 MuM (well above the physiological level) and 1.5 mM (near the physiological level), respectively.