Carroll R G, Thomas J M
Department of Physiology, East Carolina University School of Medicine, Greenville, North Carolina 27858-4354, USA.
Shock. 1994 Mar;1(3):213-6. doi: 10.1097/00024382-199403000-00009.
Divalent cation movement characterizes the final common pathway of cellular death from ischemic or metabolic injury. The influx of calcium is an essential step in cellular death. We hypothesized that intracellular magnesium levels may change during the progression to cellular death. Verapamil-sensitive changes in free ionized intracellular Mg2+ ([Mg2+[i) and Ca2+ ([Ca2+]i) levels were estimated in transformed T-lymphocytes exposed to metabolic inhibitors. Separate experiments used a Mg(2+)-sensitive fluoroprobe, fura-2 (Ex 1,344, Ex 2,376, Em 500), and a Ca(2+)-sensitive fluoroprobe, fura-2 (Ex 1,340, Ex 2,380, Em 510). Chemical anoxia (sodium cyanide 1 mM, iodoacetic acid 10 mM) caused a gradual increase in [Ca2+]i (control 126 +/- 13 nM) to > 1 mM by 10 min. This increase in [Ca2+]i was not affected by verapamil treatment. In separate experiments, [Mg2+]i levels were monitored during chemical anoxia. The specificity of mag-fura for Mg2+ over Ca2+ was reflected in the absence of a response to the lymphocyte Ca2+ mobilizer OKT-3. Uncorrected control [Mg2+]i levels (.4 +/- .1 mM) were not affected by the combined cyanide-iodoacetate treatment. A small increase in mag-fura-2 fluorescence was noted, probably due to binding of Ca2+ to the fluoroprobe when [Ca2]i exceeded 1 mM. Elimination of Ca2+ from the extracellular buffer increased the resting estimate of intracellular [Mg2+] to 1.6 + .1 mM. These results indicate that 1) extracellular Ca2+ can interfere with the fluorescent determination of intracellular magnesium concentration, and 2) intracellular free Mg2+ concentrations do not change in this cell line during chemical anoxia.
二价阳离子的移动是缺血或代谢损伤导致细胞死亡的最终共同途径的特征。钙的内流是细胞死亡的一个关键步骤。我们推测在细胞死亡的进程中细胞内镁水平可能会发生变化。在暴露于代谢抑制剂的转化T淋巴细胞中，评估了对维拉帕米敏感的游离细胞内Mg2+（[Mg2+]i）和Ca2+（[Ca2+]i）水平的变化。单独的实验使用了一种Mg(2+)敏感荧光探针fura-2（激发波长1 344纳米、激发波长2 376纳米、发射波长500纳米）和一种Ca(2+)敏感荧光探针fura-2（激发波长1 340纳米、激发波长2 380纳米、发射波长510纳米）。化学性缺氧（1毫摩尔氰化钠、10毫摩尔碘乙酸）导致[Ca2+]i（对照为126±13纳摩尔）在10分钟内逐渐升高至超过1毫摩尔。[Ca2+]i的这种升高不受维拉帕米处理的影响。在单独的实验中，在化学性缺氧期间监测[Mg2+]i水平。mag-fura对Mg2+而非Ca2+的特异性体现在对淋巴细胞Ca2+动员剂OKT-3无反应上。未校正的对照[Mg2+]i水平（0.4±0.1毫摩尔）不受氰化物 - 碘乙酸联合处理的影响。观察到mag-fura-2荧光有小幅增加，这可能是由于当[Ca2+]i超过1毫摩尔时Ca2+与荧光探针结合所致。从细胞外缓冲液中去除Ca2+可使细胞内[Mg2+]的静息估计值增加至1.6±0.1毫摩尔。这些结果表明，1）细胞外Ca2+可干扰细胞内镁浓度的荧光测定，2）在这种细胞系中，化学性缺氧期间细胞内游离Mg2+浓度不会改变。
