title: Effect of chronic Li+ treatment on free intracellular Mg2+ in human neuroblastoma SH-SY5Y cells.
abstract: 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.
authors.affiliation: Department of Chemistry, Loyola University Chicago, Illinois 60626, USA.
authors.forename: Abde M
authors.initials: AM
authors.lastname: Abukhdeir
authors.forename: Brian T
authors.initials: BT
authors.lastname: Layden
authors.forename: Nicole
authors.initials: N
authors.lastname: Minadeo
authors.forename: Fred B
authors.initials: FB
authors.lastname: Bryant
authors.forename: Evan B
authors.initials: EB
authors.lastname: Stubbs
authors.forename: Duarte
authors.initials: D
authors.lastname: Mota de Freitas
mesh_terms: 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
chemical_list: D008094:Lithium; D008274:Magnesium