Regulation of intracellular Mg2+ by superoxide in amnion cells.
Changes of intracellular free Mg2+ concentration ([Mg2+]i) in human amnion cells induced by superoxide anion were determined using a highly Mg(2+)-sensitive fluorescent dye Mg(2+)-fura2 or Mg(2+)-indol. Superoxide anion, produced by addition of xanthine oxidase to hypoxanthine, induced decrease of [Mg2+]i. The decrease was significantly inhibited by an anion channel blocker, 4,4'diisothiocyano-2,2' disulfonic acid stilbene (DIDS). Superoxide dismutase (SOD), injected into cells by cell fusion, also inhibited the change of [Mg2+]i, but catalase did not. Superoxide anion induced prompt increase of intracellular pH (pHi) as well as decrease of [Mg2+]i and subsequently activated the increase of intracellular free Ca2+ ([Ca2+]i) and the release of arachidonate. In contrast to superoxide anion, NH4Cl which induces increase of pHi in amnion cells increased [Mg2+]i. The elevation of basal level of [Mg2+]i by Mg(2+)-ionophore inhibited the change of [Ca2+]i and the release of arachidonate induced by superoxide anion. These results suggest that superoxide anion, transported through anion channels into cells, decreases [Mg2+]i directly, not due to a pH-effect and that the decrease of [Mg2+]i may regulate biological functions of the cells via increase of [Ca2+]i.
Masumoto
N
N
Department of Obstetrics and Gynecology, Osaka University Medical School, Japan.
Tasaka
K
K
Mizuki
J
J
Miyake
A
A
Tanizawa
O
O
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000650:Amnion / Q000378:metabolism*; D016718:Arachidonic Acid / Q000378:metabolism; D002459:Cell Fusion; D002478:Cells, Cultured; D004910:Erythrocyte Membrane / Q000502:physiology; D005456:Fluorescent Dyes; D016166:Free Radical Scavengers; D006801:Humans; D019271:Hypoxanthine; D007042:Hypoxanthines / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000494:pharmacology*; D014741:Video Recording; D014969:Xanthine Oxidase / Q000378:metabolism
D005456:Fluorescent Dyes; D016166:Free Radical Scavengers; D007042:Hypoxanthines; D013481:Superoxides; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D016718:Arachidonic Acid; D019271:Hypoxanthine; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D008274:Magnesium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid