Rehder Dieter, Haupt Erhard T K, Müller Achim
Chemistry Department, University of Hamburg, 20146 Hamburg, Germany.
Magn Reson Chem. 2008;46 Suppl 1:S24-9. doi: 10.1002/mrc.2343.
Li+ ions can interplay with other cations intrinsically present in the intra- and extra-cellular space (i.e. Na+, K+, Mg2+ and Ca2+) have therapeutic effects (e.g. in the treatment of bipolar disorder) or toxic effects (at higher doses), likely because Li+ interferes with the intra-/extra-cellular concentration gradients of the mentioned physiologically relevant cations. The cellular transmembrane transport can be modelled by molybdenum-oxide-based Keplerates, i.e. nano-sized porous capsules containing 132 Mo centres, monitored through 6/7Li as well as 23Na NMR spectroscopy. The effects on the transport of Li+ cations through the 'ion channels' of these model cells, caused by variations in water amount, temperature, and by the addition of organic cationic 'plugs' and the shift reagent Dy(PPP)2 are reported. In the investigated solvent systems, water acts as a transport mediator for Li+. Likewise, the counter-transport (Li+/Na+, Li+/K+, Li+/Cs+ and Li+/Ca2+) has been investigated by 7Li NMR and, in the case of Li+/Na+ exchange, by 23Na NMR, and it has been shown that most (in the case of Na+ and K+, all (Ca2+) or almost none (Cs+) of the Li cations is extruded from the internal sites of the artificial cell to the extra-cellular medium, while Na+, K+ and Ca2+ are partially incorporated.
锂离子可以与细胞内和细胞外空间中原本存在的其他阳离子（即Na⁺、K⁺、Mg²⁺和Ca²⁺）相互作用，具有治疗作用（例如在双相情感障碍的治疗中）或毒性作用（在较高剂量时），这可能是因为锂离子会干扰上述生理相关阳离子的细胞内/外浓度梯度。细胞跨膜运输可以用基于氧化钼的开普勒酸盐来模拟，即含有132个钼中心的纳米级多孔胶囊，通过⁶/⁷Li以及²³Na核磁共振光谱进行监测。报告了由水量、温度变化以及添加有机阳离子“塞子”和位移试剂Dy(PPP)₂对锂离子通过这些模型细胞的“离子通道”运输的影响。在所研究的溶剂体系中，水作为锂离子的运输介质。同样，通过⁷Li核磁共振研究了反向运输（Li⁺/Na⁺、Li⁺/K⁺、Li⁺/Cs⁺和Li⁺/Ca²⁺），对于Li⁺/Na⁺交换，通过²³Na核磁共振进行了研究，结果表明，大多数（对于Na⁺和K⁺，全部（Ca²⁺）或几乎没有（Cs⁺）的锂阳离子从人工细胞的内部位点挤出到细胞外介质中，而Na⁺、K⁺和Ca²⁺则部分被纳入。
