OXIDANT MECHANISMS IN DRUG-INDUCED HEPATIC NECROSIS

许多毒素通过代谢产生化学反应来杀死细胞 转而引起细胞分子变化的中间体， 损害细胞结构和功能，导致丧失活力。 在这样的研究中观察到了许多化学和生化变化，但并不是全部 它们在引发破坏方面起到了至关重要的作用。 然而，我们认识到有三种主要的组织改变类型： 烷基化、氧化和过氧化。研究……的一个困难 氧化应激所致的肝坏死一直缺乏一种动物 模特。尽管活性氧物种的机械参与 被建议用于治疗由多种药物引起的组织损伤 缺血后再流，许多已知的机制 通过它，活性氧物种杀死细胞已经发展到 在体外进行的研究，特别是在分离或培养的大鼠中 肝细胞。我们发现敌草快能在体内产生中心细胞坏死。 雄性费舍尔-344只大鼠和多条证据表明 坏死是通过产生活性氧来调节的。这 模型进行了进一步研究，以努力理解 哪些活性氧物种和氧化剂应激可在体内杀死细胞并 制定用于区分这些细胞示例的定量标准 体内死亡可能是由体内的氧化机制介导的 它的致死效应是通过其他机制表达的。 DQUAT急性肝坏死模型的研究 演示了与以下假设产生的一些重要差异 体外研究，特别是细胞迁移的作用 硫醇/二硫键比率和蛋白质硫醇的耗竭。这些研究 揭示了脂类的一个明显的关键作用 体内活性氧损伤表达中的过氧化作用 铁的化学活性络合物的可用性似乎是一种 过氧化损伤和细胞死亡的基本决定因素。这些研究 本提案中描述的是旨在应用特定于化学物质的 脂类含量调查的分析方法 过氧化反应是敌草快诱导的活体肝坏死的原因 化学活性铁物种在这些过程中所起的作用。 这些方法和途径以及在 这些研究将应用于对这一假设的批判性检验。 氧化应激机制导致由 对乙酰氨基酚，四氯化碳。因为后两个特工 都是如此重要的模型肝毒素，建议的研究是针对 对我们理解细胞机制至关重要的问题 活体死亡。

Many toxins kill cells by the metabolic generation of chemically reactive intermediates that in turn produce alterations in cellular molecules, compromising cell structure and function, leading to loss of viability. Many chemical and biochemical changes are observed in such studies, not all of which are involved critically in the initiation of damage. Nevertheless, three major classes of tissue alteration are recognized: alkylation, oxidation, and peroxidation. A difficulty in the study of oxidant stress-induced hepatic necrosis has been the lack of an animal model. Although the mechanistic involvement of reactive oxygen species has been proposed for tissue damage initiated by a number of drugs and by reflow following ischemia, much of what is known about the mechanisms through which reactive oxygen species kill cells has been developed in studies conducted in vitro, particularly in isolated or cultured rat hepatocytes. We have found that diquat produces centribolular necrosis in male Fischer-344 rats and several lines of evidence indicate that this necrosis is mediated by the generation of reactive oxygen species. This model has been studied further in an effort to understand the manner in which reactive oxygen species and oxidant stress kills cells in vivo and to develop quantitative criteria for distinguishing those examples of cell death in vivo that may be mediated by oxidant mechanisms from those in which the lethal effects ar expressed through other mechanisms. Investigations of the diquat model of acute hepatic necrosis have demonstrated some important differences from the hypotheses generated from studies in vitro, particularly the role of shifts in cellular thiol/disulfide ratios and the depletion of protein thiols. These studies of the diquat model have revealed an apparently critical role of lipid peroxidation in the expression of reactive oxygen injury in vivo, and that the availability of chemically reactive chelates of iron appears to be an essential determinant of peroxidation damage and cell death. The studies described in this proposal are designed to apply chemically specific methods of analysis to the investigation of the extent to which lipid peroxidation is responsible for diquat-induced hepatic necrosis in vivo and the role played by chemically reactive iron species in these processes. These methods and approaches and the quantitative criteria developed in these studies will be applied to a critical examination of the hypothesis that oxidant stress mechanisms contribute to hepatic necrosis initiated by acetaminophen an by carbon tetrachloride. Because the latter two agents are such important model hepatotoxins, the proposed studies are directed at issues that are fundamental to our understanding of the mechanisms of cell death in vivo.