title: Na+/Mg2+ transporter acts as a Mg2+ buffering mechanism in PC12 cells.
abstract: Mg(2+) buffering mechanisms in PC12 cells were demonstrated with particular focus on the role of the Na(+)/Mg(2+) transporter by using a newly developed Mg(2+) indicator, KMG-20, and also a Na(+) indicator, Sodium Green. Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP), a protonophore, induced a transient increase in the intracellular Mg(2+) concentration ([Mg(2+)](i)). The rate of decrease of [Mg(2+)](i) was slower in a Na(+)-free extracellular medium, suggesting the coupling of Na(+) influx and Mg(2+) efflux. Na(+) influxes were different for normal and imipramine- (a putative inhibitor of the Na(+)/Mg(2+) transporter) containing solutions. FCCP induced a rapid increase in [Na(+)](i) in the normal solution, while the increase was gradual in the imipramine-containing solution. The rate of decrease of [Mg(2+)](i) in the imipramine-containing solution was also slower than that in the normal solution. From these results, we show that the main buffering mechanism for excess Mg(2+) depends on the Na(+)/Mg(2+) transporter in PC12 cells.
authors.affiliation: School of Fundamental Science and Technology, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kubota
authors.forename: Kentaro
authors.initials: K
authors.lastname: Tokuno
authors.forename: Jun
authors.initials: J
authors.lastname: Nakagawa
authors.forename: Yoshiichiro
authors.initials: Y
authors.lastname: Kitamura
authors.forename: Hiroto
authors.initials: H
authors.lastname: Ogawa
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Koji
authors.initials: K
authors.lastname: Suzuki
authors.forename: Kotaro
authors.initials: K
authors.lastname: Oka
mesh_terms: D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology; D000818:Animals; D017920:Antiporters / Q000378:metabolism*; D001692:Biological Transport; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D007099:Imipramine / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D007477:Ions; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D016716:PC12 Cells; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D013054:Spectrophotometry, Atomic; D013997:Time Factors; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D018759:Adrenergic Uptake Inhibitors; D017920:Antiporters; D007476:Ionophores; D007477:Ions; D014475:Uncoupling Agents; C046250:sodium-magnesium antiporter; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D012964:Sodium; D008274:Magnesium; D007099:Imipramine