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Differential Uptake of Lithium Isotopes by Rat Cerebral Cortex and Its Effect on Inositol Phosphate Metabolism
Author(s) -
Sherman William R.,
Munsell Ling Y.,
Wong YunHua H.
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb02765.x
Subject(s) - inositol , lithium (medication) , inositol phosphate , endocrinology , chemistry , medicine , metabolism , phosphate , cerebral cortex , cortex (anatomy) , isotope , biochemistry , biology , receptor , neuroscience , physics , quantum mechanics
Twenty hours following the subcutaneous administration of 5 mEq/kg doses of 6 LiCl and 7 LiCl to two groups of rats, the cerebral cortex molar ratio of 6 Li + / 7 Li + is 1.5. The effects of the lithium isotopes on cortex myo ‐inositol and myo ‐inositol‐1 ‐phosphate levels are the same as we have reported earlier: a Li + concentration‐dependent lowering of myo ‐inositol and increase in myo ‐inositol‐1‐phosphate. Thus 6 LiCl, when administered at the same dose as 7 LiCl, produces the larger effect on inositol metabolism. When the 6 LiCl and 7 LiCl doses were adjusted to 5 mEq/kg and 7 mEq/kg, respectively, the cortical lithium myo ‐inositol and myo ‐inositol‐1‐phosphate levels of each group of animals became approximately equal, suggesting that the isotope effect occurs at the level of tissue uptake, but not on inositol phosphate metabolism. The inhibition of myo ‐inositol‐1‐phosphatase by the two lithium isotopes in vitro showed no differential effect. The isotope effect on cerebral cortex uptake of lithium is in the same direction as that reported by others for erythrocytes and for the CSF/plasma ratio, but of larger magnitude.