Effect of chronic Li+ treatment on free intracellular Mg2+ in human neuroblastoma SH-SY5Y cells.
OBJECTIVE
Previous findings have demonstrated Li+/Mg2+ competition at therapeutic intracellular Li+ levels after acute Li+ treatment in human neuroblastoma SH-SY5Y cells. In the current study, we examined whether Li+/Mg2+ competition exists at therapeutically relevant extra- and intracellular [Li+] after chronic Li+ loading times.


METHODS
In human neuroblastoma cells, intracellular free Mg2+ was determined by fluorescence spectroscopy with the fluorophore furaptra. Intracellular Li+ and Mg2+ were measured by atomic absorption spectrophotometry.


RESULTS
After loading of the neuroblastoma cells with 1-2 mM extracellular Li+ for 24-72 h, the observed, increased intracellular free [Mg2+] levels were significantly higher (p < 0.03) than those in matched Li+ free cells, and intracellular [Li+] was found to be at therapeutic intracellular levels (0.7-1.5 mM).


CONCLUSIONS
The results demonstrate that Li+/Mg2+ competition exists after chronic treatment with Li+ at therapeutically relevant intracellular Li+ levels in neuroblastoma cells. We found differences between acute and chronic Li+ treatment effects on the extent of Li+/Mg2+ competition. Possible reasons for these differences are discussed.
Abukhdeir
Abde M
AM
Department of Chemistry, Loyola University Chicago, Illinois 60626, USA.
Layden
Brian T
BT
Minadeo
Nicole
N
Bryant
Fred B
FB
Stubbs
Evan B
EB
Mota de Freitas
Duarte
D
D000704:Analysis of Variance; D001714:Bipolar Disorder / Q000188:drug therapy / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007424:Intracellular Fluid / Q000737:chemistry; D017136:Ion Transport / Q000187:drug effects; D008094:Lithium / Q000032:analysis / Q000494:pharmacology*; D008274:Magnesium / Q000032:analysis / Q000378:metabolism*; D009447:Neuroblastoma; D014407:Tumor Cells, Cultured
D008094:Lithium; D008274:Magnesium