CHEMICAL TOXICITY AND GLUTATHIONE REGULATION

本研究的目的是明确细胞的作用和地位， 在细胞防御系统中起作用的成分， 从有毒化学品中提取的中间体。 被调查的特工 谷胱甘肽（GSH）、维生素E（α-生育酚）和维生素C （L-抗坏血酸）。 这些研究是用大鼠进行的， 细胞防御受损的肝细胞模型 抗化学诱导的细胞损伤和死亡的机制。 模型 包括具有以下之一细胞：1）不可逆失活的谷胱甘肽 还原酶，2）由于被分离，谷胱甘肽过氧化物酶水平低 从大鼠硒缺乏饮食，3）维生素E缺乏症，由于 从缺乏维生素E饮食的大鼠中分离出来，4）受到以下因素的影响： 从培养基中省略钙和5）经历GSH的消耗， GSH消耗剂，并置于不含硫氨基的培养基中 acids. 这些肝细胞模型被用于研究 假设细胞可能有一个共同的途径损伤和死亡， 暴露于许多有毒化学物质的细胞防御系统的损失， 允许内源性氧化应激促进显著的 细胞活力丧失的程度。 提出的内源性机制 氧化应激和化学诱导的氧化应激是改变 某些蛋白质巯基的体内平衡，导致 细胞存活所需的硫醇/二硫化物氧化还原平衡。 一项重大努力 将致力于阐明蛋白质巯基混合 急性细胞损伤时形成的二硫化物。 此外，本发明还提供了一种方法， 实验旨在确定GSH，维生素E和维生素C是否 暴露于毒性试剂期间肝细胞中的水平，包括 环境因子是这些细胞保护因子的结果 具有电子抗氧化性能，因此可能"节省" 方面的影响. 正在努力确定细胞内氧化还原 GSH、维生素C和E之间存在关系， 电子和氢转移的不同速率， 在急性化学反应期间和之后维持细胞活力的作用 诱导细胞损伤。 具有特定磷脂的体外模型正在被 用于提供解释结果的基础 损害肝细胞模型实验。 正在使用的化学品模型 包括甲磺酸乙酯、溴苯、对乙酰氨基酚、A23187 阿霉素、叔丁基过氧化氢、过氧化甲乙酮和 1，3-双-（20-乙基）-1-亚硝基脲（BCNU）。

The research objective is to define the role and status of cellular constituents that function in cellular defense systems against reactive intermediates derived from toxic chemicals. The agents to be investigated are glutathione (GSH), vitamin E (alpha-tocopherol) and vitamin C (L-ascorbic acid). The studies are being conducted with rat hepatocytemodels that have been compromised in their cellular defense mechanisms against chemically induced cell injury and death. The models include cells that have either; 1) irreversibly inactivated glutathione reductase, 2) low levels of glutathione peroxidase due to being isolated from rats on a selenium deficient diet, 3) vitamin E deficiency due to being isolated from rats on a vitamin E deficient diet, 4) compromised by omission of calcium from the medium and 5) undergone depletion of GSH by GSH-depleting agents and placed in a medium that is free of sulfur amino acids. These hepatocyte models are being utilized to investigate the hypothesis that cells may have as a common pathway to injury and death from exposure to many toxic chemicals the loss of cellular defense systems which allows for endogenous oxidative stress to contribute to a significant degree to loss of cell viability. The mechanism proposed for endogenous oxidative stress and chemically induced oxidative stress is the alteration of the homeostasis of certain protein sulfhydryls leading to a loss of the thiol/disulfide redox balance needed for cell survival. A major effort will be devoted to the elucidation of the protein sulfhydryl mixed disulfides that are formed during acute cell injury. In addition, experiments are designed to determine if the GSH, vitamin E and vitamin C levels in hepatocytes during exposure to toxic agents including environmental agents are the result of these cellular protective agents having on electron antioxidant properties and thus possible "sparing" effects. Efforts are being made to determine if an intracellular redox relationship exists between GSH, vitamins C and E that involves differential rates of electron and hydrogen transfers that may have a key role in the maintenance of cell viability during and after acute chemically induced cell injury. In vitro models with specific phospholipids are being utilized to provide the basis for the interpretation of results from the compromised hepatocyte model experiments. Model chemicals being used include ethyl methanesulfonate, bromobenzene, acetaminophen, A23187, Adriamycin, t-butyl hydroperoxide, methyl ethylketone peroxide and 1,3-bis-(20chlorethyl)-1-nitrosourea (BCNU).