Bellomo G, Nicotera P, Orrenius S
Eur J Biochem. 1984 Oct 1;144(1):19-23. doi: 10.1111/j.1432-1033.1984.tb08425.x.
Addition of ATP to the incubation medium of freshly isolated rat hepatocytes causes a marked inhibition of the efflux of Ca2+ from the cells, and its accumulation in intracellular compartments. After an initial rise in cytosolic free Ca2+ concentration, as indicated by the activation of phosphorylase, Ca2+ is preferentially sequestered in the mitochondria, without any apparent contribution by the endoplasmic reticulum. Impairment of mitochondrial Ca2+ homeostasis by pyridine nucleotide oxidation associated with tert-butyl hydroperoxide metabolism, prevents the ATP-dependent cellular Ca2+ accumulation and causes a release of Ca2+ from the hepatocytes into the medium. Conversely, maintenance of the mitochondrial pyridine nucleotides in a more reduced state, e. g. in presence of 3-hydroxybutyrate in the medium, prevents this hydroperoxide-induced release of intracellular Ca2+. Under conditions of impaired mitochondrial Ca2+ sequestration, there appears to be a redistribution of a minor fraction of the intracellular Ca2+ from the mitochondria to the endoplasmic reticulum. Our results provide additional evidence for the critical involvement of the plasma membrane Ca2+-extruding system in the physiological regulation of the cytosolic free Ca2+ concentration in hepatocytes, and suggest that the mitochondria play a more important role than the endoplasmic reticulum in the regulation of the cytosolic free Ca2+ level when the plasma membrane Ca2+ pump is inhibited.
向新鲜分离的大鼠肝细胞孵育培养基中添加ATP会显著抑制Ca2+从细胞外流及其在细胞内区室中的积累。如磷酸化酶激活所示，在细胞质游离Ca2+浓度最初升高后，Ca2+优先被隔离在线粒体中，内质网没有任何明显作用。与叔丁基过氧化氢代谢相关的吡啶核苷酸氧化会损害线粒体Ca2+稳态，阻止ATP依赖的细胞Ca2+积累，并导致Ca2+从肝细胞释放到培养基中。相反，将线粒体吡啶核苷酸维持在更还原的状态，例如培养基中存在3-羟基丁酸时，可防止这种过氧化氢诱导的细胞内Ca2+释放。在线粒体Ca2+隔离受损的情况下，似乎有一小部分细胞内Ca2+从线粒体重新分布到内质网。我们的结果为质膜Ca2+挤出系统在肝细胞细胞质游离Ca2+浓度的生理调节中的关键作用提供了额外证据，并表明当质膜Ca2+泵受到抑制时，线粒体在细胞质游离Ca2+水平的调节中比内质网发挥更重要的作用。
