Bader M F, Thiersé D, Aunis D, Ahnert-Hilger G, Gratzl M
J Biol Chem. 1986 May 5;261(13):5777-83.
Addition of Staphylococcus aureus alpha-toxin to adult bovine chromaffin cells maintained in primary culture causes permeabilization of cell membrane as shown by the release of intracellular 86Rb+. The alpha-toxin does not provoke a spontaneous release of either catecholamines or chromogranin A, a protein marker of the secretory granule, showing the integrity of the secretory vesicle membrane. However the addition of micromolar free Ca2+ concentration induced the co-release of noradrenaline and chromogranin A. In alpha-toxin-treated cells, the released chromogranin A could not be sedimented and lactate dehydrogenase was still associated within cells, which provides direct evidence that secretory product is liberated by exocytosis. By contrast, permeabilization of cells with digitonin caused a Ca2+-dependent but also a Ca2+-independent release of secretory product, a dramatic loss of lactate dehydrogenase, as well as release of secretory product in a sedimentable form. Ca2+-dependent exocytosis from alpha-toxin-permeabilized cells required Mg2+-ATP and did not occur in the presence of other nucleotides. Thus alpha-toxin is a convenient tool to permeabilize chromaffin cells, and has the advantage of keeping intracellular structures, specifically the exocytotic machinery, intact.
向原代培养的成年牛嗜铬细胞中添加金黄色葡萄球菌α-毒素会导致细胞膜通透性增加，这可通过细胞内86Rb+的释放得以证明。α-毒素不会引发儿茶酚胺或嗜铬粒蛋白A（分泌颗粒的一种蛋白质标志物）的自发释放，这表明分泌泡膜是完整的。然而，添加微摩尔浓度的游离Ca2+会诱导去甲肾上腺素和嗜铬粒蛋白A的共同释放。在α-毒素处理的细胞中，释放出的嗜铬粒蛋白A无法沉淀，乳酸脱氢酶仍与细胞相关联，这提供了分泌产物通过胞吐作用释放的直接证据。相比之下，用洋地黄皂苷使细胞通透会导致分泌产物的Ca2+依赖性释放以及Ca2+非依赖性释放、乳酸脱氢酶的大量损失，以及分泌产物以可沉淀形式释放。α-毒素通透的细胞中Ca2+依赖性胞吐作用需要Mg2+-ATP，并且在存在其他核苷酸时不会发生。因此，α-毒素是使嗜铬细胞通透的便利工具，具有保持细胞内结构（特别是胞吐机制）完整的优点。
