钙离子和镁离子对A-431人表皮癌细胞中ATP依赖性45钙离子内流的影响。

Effects of Ca2+ and Mg2+ on ATP-dependent 45Ca2+ influx in A-431 human epidermoidal carcinoma cells.

作者信息

Sugita K, Hosoi K, Shioda Y, Ueha T

机构信息

Department of Oral Physiology, Meikai University School of Dentistry, Saitama, Japan.

出版信息

Biochem Cell Biol. 1991 Jan;69(1):29-35. doi: 10.1139/o91-004.

DOI:10.1139/o91-004

PMID:2043341

Abstract

Upon stimulation with 10(-6) -10(-3) M ATP, A-431 human epidermoidal carcinoma cells incorporated radioactive calcium from their medium in a temperature-dependent manner. The rate of incorporation of 45Ca2+ was rapid for the initial 5 min, but decreased immediately thereafter. The preincubation of cells for 2 h in medium depleted of both Ca2+ and Mg2+ abolished the ATP-dependent 45Ca2+ incorporation, irrespective of whether or not the subsequent incubation medium contained Mg2+ ions. ATP-dependent 45Ca2+ incorporation could be restored by a second preincubation (1 h) in medium containing 1 mM Mg2+, but no Ca2+. The Mg2+ ions in the second preincubation medium could be replaced by Ca2+, Co2+, or Cu2+ for restoration of such activity. Elevation of inositol trisphosphate (InsP3) was observed in cells depleted of either Ca2+ or Mg2+, but not in cells depleted of both ions. A parallel effect was observed in changes in [Ca2+]i. Since the concentration of cytosolic calcium ions does not change by incubation of cells in medium depleted of and (or) restored with calcium ions, we conclude that either calcium or magnesium ions associated with some cellular component(s) are responsible for production of InsP3, which then supposedly mobilizes Ca2+ and provokes 45Ca2+ influx.

摘要

用10⁻⁶ - 10⁻³ M的ATP刺激时，A - 431人表皮癌细胞以温度依赖的方式从培养基中摄取放射性钙。在最初的5分钟内，⁴⁵Ca²⁺的摄取速率很快，但此后立即下降。将细胞在不含Ca²⁺和Mg²⁺的培养基中预孵育2小时，无论随后的孵育培养基中是否含有Mg²⁺离子，都会消除ATP依赖的⁴⁵Ca²⁺摄取。通过在含有1 mM Mg²⁺但不含Ca²⁺的培养基中进行第二次预孵育（1小时），可以恢复ATP依赖的⁴⁵Ca²⁺摄取。第二次预孵育培养基中的Mg²⁺离子可以被Ca²⁺、Co²⁺或Cu²⁺替代以恢复这种活性。在缺乏Ca²⁺或Mg²⁺的细胞中观察到肌醇三磷酸（InsP3）升高，但在缺乏这两种离子的细胞中未观察到。在[Ca²⁺]i的变化中也观察到了类似的效应。由于在不含钙离子和（或）用钙离子恢复的培养基中孵育细胞时，胞质钙离子浓度没有变化，我们得出结论，与某些细胞成分相关的钙离子或镁离子负责InsP3的产生，然后InsP3可能会动员Ca²⁺并引发⁴⁵Ca²⁺内流。