Tissue Localisation and Transport of Lithium

One of the problems in the study of lithium action is the lack of precision in localisation of the ion and in the measurement of its movements between cells and between tissues. This lack of precision arises partly because lithium is a very mobile ion, partly because of its widespread distribution in the body, and partly because of the difficulties of lithium analysis. Analytical problems generally stem 

Lithium metabolism and transport cannot be studied directly, because the lack of useful radioisotopes has limited the metabolic information available. Lithium has five isotopes, three of which have extremely short half lives (0.8,0.2, 10 s). Lithium occurs naturally as a mixture of the two stable isotopes Li (95.58%) and Li (7.42%), which may be determined using Atomic Absorption Spectroscopy, Nuclear Magnetic Resonance Spectroscopy, or Neutron Activation analysis. Under normal circumstances it is impossible to identify isotopes by using AAS, because the spectral resolution of the spectrometer is inadequate. We have previously reported the use of ISAAS in the determination of lithium pharmacokinetics. Briefly, the shift in the spectrum from Li to Li is 0.015 nm which is identical to the separation of the two lines of the spectrum. Thus, the spectrum of natural lithium is a triplet. By measuring the light absorbed from hollow cathode lamps of each lithium isotope, a series of calibration curves is constructed, and the proportion of each isotope in the sample is determined by solution of the appropriate exponential equation. By using a dual-channel atomic absorption spectrometer, the two isotopes may be determined simultaneously. -  

The microlocalisation technique with the stable isotope Li uses a beam of neutrons in an atomic reactor. The Li nucleus absorbs a neutron and immediately undergoes fission to produce an a-particle and a H atom, which create tracks in a suitable detector placed in contact with Li-containing tissue. The tissue distribution in the rat, brain lithium distribution in the mouse and the rat, ° distribution in the mouse embryo, kinetics in the mouse brain, and distribution in mutant strains of mice with dysmyelination have been studied. 

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