Babich L G, Borisova L A, Shlykov S G, Titus O V, Kosterin S A
Ukr Biokhim Zh (1999). 2004 Sep-Oct;76(5):52-60.
In experiments, which were carried out with the use of a radioactive label (45Ca2+) on the suspension of rat uterus myocytes treated by digitonin solution (0.1 mg/ml), influence of Mg ions and spermine on Mg2+, ATP-dependent Ca2+ transport in mitochondria and sarcoplasmic reticulum was investigated. Ca2+ accumulation in mitochondria (1324 +/- 174 pmol Ca2+/10(6) cells for 1 min - the control) was tested as such which was not sensitive to thapsigargin (100 nM) and was blocked by ruthenium red (10 microM). Oxalate-stimulated Ca2+ accumulation in sarcoplasmic reticulum (136 +/- 17 pmol Ca2+/10(6) cells for 1 min - the control) was tested as such which was not sensitive to ruthenium red and was blocked by thapsigargin. It has been shown, that initial speed and level of energy-dependent Ca2+ accumulation in mitochondria considerably exceeded the values of these parameters for sarcoplasmic reticulum Ca2+-accumulation system. Ca2+ accumulation kinetic in mitochondria was characterized by a steady-state phase (for 5-10 min. of incubation) while accumulation kinetic of this cation in sarcoplasmic reticulum corresponded to zero order reaction. Increase of Mg2+ concentration up to 5 mM led to activation of Ca2+-accumulation systems in mitochondria and sarcoplasmic reticulum (values of activation constants K(Mg) for Mg2+ were 2.8 and 0.6 mM, accordingly). Concentration dependence of spermine action on Ca2+ accumulation in mitochondria was described by a dome-shaped curve with a maximum at 1 mM spermine. In case of sarcoplasmic reticulum Ca2+ pump only the inhibition phase was tested at spermine concentration above 1 mM. However values of inhibition constants for both transporting systems were practically identical--5.2 +/- 0.6 and 5.7 +/- 0.7 mM, accordingly. Hence, Mg ions carry out the important role in regulation of energy-dependent Ca2+ transporting systems both in uterus smooth muscle mitochondria and sarcoplasmic reticulum. Spermine acts first of all on mitochondrial calcium uniporter.
在用洋地黄皂苷溶液（0.1mg/ml）处理的大鼠子宫肌细胞悬液上，利用放射性标记（45Ca2+）进行实验，研究了镁离子和精胺对线粒体及肌浆网中镁离子、ATP依赖的钙离子转运的影响。线粒体中钙离子的积累（对照组为1324±174pmol Ca2+/10(6)个细胞/1分钟）经测试对毒胡萝卜素（100nM）不敏感，但被钌红（10μM）阻断。草酸盐刺激的肌浆网中钙离子的积累（对照组为136±17pmol Ca2+/10(6)个细胞/1分钟）经测试对钌红不敏感，但被毒胡萝卜素阻断。结果表明，线粒体中能量依赖的钙离子积累的初始速度和水平大大超过了肌浆网钙离子积累系统的这些参数值。线粒体中钙离子积累动力学的特征是一个稳态阶段（孵育5 - 10分钟），而该阳离子在肌浆网中的积累动力学符合零级反应。将镁离子浓度提高到5mM会导致线粒体和肌浆网中钙离子积累系统的激活（镁离子的激活常数K(Mg)值分别为2.8和0.6mM）。精胺对线粒体中钙离子积累作用的浓度依赖性由一条钟形曲线描述，在精胺浓度为1mM时达到最大值。对于肌浆网钙离子泵，仅在精胺浓度高于1mM时测试了抑制阶段。然而，两个转运系统的抑制常数的值实际上是相同的——分别为5.2±0.6和5.7±0.7mM。因此，镁离子在子宫平滑肌线粒体和肌浆网中能量依赖的钙离子转运系统的调节中起着重要作用。精胺首先作用于线粒体钙单向转运体。
