Masumoto N, Tasaka K, Mizuki J, Miyake A, Tanizawa O
Department of Obstetrics and Gynecology, Osaka University Medical School, Japan.
Biochem Biophys Res Commun. 1992 Jan 31;182(2):906-12. doi: 10.1016/0006-291x(92)91818-b.
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.
使用高度镁敏感荧光染料Mg(2+)-fura2或Mg(2+)-吲哚测定超氧阴离子诱导的人羊膜细胞内游离镁离子浓度([Mg2+]i)的变化。向次黄嘌呤中加入黄嘌呤氧化酶产生的超氧阴离子诱导[Mg2+]i降低。阴离子通道阻滞剂4,4'-二异硫氰酸-2,2'-二磺酸芪(DIDS)显著抑制了这种降低。通过细胞融合注入细胞的超氧化物歧化酶(SOD)也抑制了[Mg2+]i的变化，但过氧化氢酶没有。超氧阴离子诱导细胞内pH值(pHi)迅速升高以及[Mg2+]i降低，随后激活细胞内游离钙离子([Ca2+]i)的增加和花生四烯酸的释放。与超氧阴离子相反，在羊膜细胞中诱导pHi升高的氯化铵增加了[Mg2+]i。Mg(2+)-离子载体使[Mg2+]i基础水平升高，抑制了超氧阴离子诱导的[Ca2+]i变化和花生四烯酸的释放。这些结果表明，超氧阴离子通过阴离子通道进入细胞，直接降低[Mg2+]i，而非由于pH效应，并且[Mg2+]i的降低可能通过增加[Ca2+]i来调节细胞的生物学功能。
