Stacey N H, Klaassen C D
J Toxicol Environ Health. 1982 Mar;9(3):439-50. doi: 10.1080/15287398209530176.
Isolated hepatocytes provide a suitable system for investigation of various aspects of the mechanism of a toxic response. The mechanism by which most chemicals induce hepatotoxicity is still not known. Evidence that phospholipases may play a role in cellular injury has been reported. In the present study the effects of reported inhibitors of phospholipase A2 (quinacrine, chlorpromazine, dexamethasone, and dibutyryl cyclic AMP) on diethyl maleate (DEM)-induced lipid peroxidation, reduced glutathione (GSH) depletion, and cellular injury were examined in isolated hepatocyte suspensions. Hepatocytes were incubated for 7 h under control conditions or with (1) DEM (4 mM), (2) one of the inhibitors (quinacrine, 10, 50, or 150 microM; chlorpromazine, 50 microM; dexamethasone, 0.1, 0.5, 1, or 2.5 mM; dibutyryl cyclic AMP, 0.1, 0.5, 1, or 2.5 mM) or aspirin (500 microM), or (3) a combination of DEM and one of the inhibitors or aspirin to determine their effect on DEM toxicity. Samples were withdrawn at hourly intervals for estimation of cellular injury (loss of intracellular K+ and lactate dehydrogenase and trypan blue exclusion index), lipid peroxidation (thiobarbituric acid reactants assay), and GSH concentration. Quinacrine and chlorpromazine inhibited DEM-induced lipid peroxidation but not cellular injury or GSH loss. This suggests that phospholipase A2 may be involved in DEM-induced lipid peroxidation but not cell damage. However, dexamethasone and dibutyryl cyclic AMP enhanced both lipid peroxidation and loss of cell viability due to DEM, suggesting novel aspects of the biochemical mechanisms of chemically induced cytotoxicity.
分离的肝细胞为研究毒性反应机制的各个方面提供了一个合适的系统。大多数化学物质诱导肝毒性的机制尚不清楚。已有报道表明磷脂酶可能在细胞损伤中起作用。在本研究中，在分离的肝细胞悬液中检测了已报道的磷脂酶A2抑制剂（奎纳克林、氯丙嗪、地塞米松和二丁酰环磷腺苷）对马来酸二乙酯（DEM）诱导的脂质过氧化、还原型谷胱甘肽（GSH）消耗和细胞损伤的影响。肝细胞在对照条件下或与（1）DEM（4 mM）、（2）一种抑制剂（奎纳克林，10、50或150 microM；氯丙嗪，50 microM；地塞米松，0.1、0.5、1或2.5 mM；二丁酰环磷腺苷，0.1、0.5、1或2.5 mM）或阿司匹林（500 microM）、或（3）DEM与一种抑制剂或阿司匹林的组合一起孵育7小时，以确定它们对DEM毒性的影响。每隔一小时取出样品，用于评估细胞损伤（细胞内钾离子和乳酸脱氢酶的损失以及台盼蓝排斥指数）、脂质过氧化（硫代巴比妥酸反应物测定）和GSH浓度。奎纳克林和氯丙嗪抑制了DEM诱导的脂质过氧化，但不抑制细胞损伤或GSH损失。这表明磷脂酶A2可能参与了DEM诱导的脂质过氧化，但不参与细胞损伤。然而，地塞米松和二丁酰环磷腺苷增强了DEM引起的脂质过氧化和细胞活力丧失，提示了化学诱导细胞毒性生化机制的新方面。
