Castilho R F, Kowaltowski A J, Meinicke A R, Bechara E J, Vercesi A E
Departamento de Bioquímica, Universidade Estadual de Campinas, Brazil.
Free Radic Biol Med. 1995 Mar;18(3):479-86. doi: 10.1016/0891-5849(94)00166-h.
The extent of swelling undergone by deenergized mitochondria incubated in KCl/sucrose medium in the presence of Ca2+ alone or Ca2+ and t-butyl hydroperoxide decreases by decreasing molecular oxygen concentration in the reaction medium; under anaerobiosis no swelling occurs. This swelling is also inhibited by the presence of exogenous catalase or by the Fe2+ chelator o-phenanthroline in a time-dependent manner. The production of protein thiol cross-linking that leads to the formation of protein aggregates induced by Ca2+ and t-butyl hydroperoxide does not occur when mitochondria are incubated in anaerobic medium or in the presence of o-phenanthroline. In addition, it is also shown that the yield of stable methyl radical adducts, obtained from rat liver mitochondria treated with t-butyl hydroperoxide and the spin trap DMPO, is reduced by addition of EGTA and increases by addition of Ca2+ ions. These data support the hypothesis that Ca2+ ions stimulate electron leakage from the respiratory chain, increasing the mitochondrial production of reactive oxygen species.
在仅存在Ca2+或同时存在Ca2+和叔丁基过氧化氢的情况下，于KCl/蔗糖培养基中孵育的去能线粒体的肿胀程度，会随着反应介质中分子氧浓度的降低而减小；在无氧条件下不会发生肿胀。外源性过氧化氢酶的存在或Fe2+螯合剂邻菲罗啉也会以时间依赖性方式抑制这种肿胀。当线粒体在厌氧培养基中或存在邻菲罗啉的情况下孵育时，由Ca2+和叔丁基过氧化氢诱导的导致蛋白质聚集体形成的蛋白质硫醇交联反应不会发生。此外，研究还表明，用叔丁基过氧化氢和自旋捕获剂DMPO处理的大鼠肝线粒体所获得的稳定甲基自由基加合物的产量，会因加入EGTA而降低，并因加入Ca2+离子而增加。这些数据支持了以下假设：Ca2+离子会刺激呼吸链中的电子泄漏，从而增加线粒体活性氧的产生。
