摘要：The cytotoxicity of reactive oxygen species and related agents toward cultured rat adrenal medullary phenochromocytoma PC12 cells was examined. These species and agents include hydrogen peroxide, linoleic acid hydroperoxide(LOOH), tert-butyl hydroperoxide, paraquat, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH), 2,2'-azobis(2,4-dimethylvaleronitrile)(AMVN), and a hypoxanthine-xanthine oxidase system. The respective 50% lethal concentrations (LC50) for undifferentiated and differentiated PC12 cells were found to be 275 and 165 μM of hydrogen peroxide, 58.3 and 35.3 μM of LOOH, 536 and 212 μM of tert-butyl hydroperoxide, 42.5 and 26.5 mM of paraquat, 79.5 and 74.5 mM of AAPH, 412 and 300 μM of AMVN, and 37.2 and 16.6 mU·ml-1 xanthine oxidase activity of the hypoxanthine-xanthine oxidase system. These results show that the differentiated cells were more susceptible to these oxidative agents than the undifferentiated cells. The glutathione peroxidase activity level of the undifferentiated cells was 2—3 times higher than the differentiated cells, the catalase activity level also tended to be higher, the superoxide dismutase activity level was higher on a per-protein-quantity basis but lower on a per-cell-number basis, and the total and reduced glutathione concentration levels were considerably higher. The enhanced susceptibility of the differentiated cells may result from decreases in the activity of glutathione peroxidase and the concentration of its substrate, reduced glutathione (GSH). Further, the preincubation of PC12 cells with α-tocopherol or L-buthionine-(R,S)-sulfoximine(BSO) lowered or enhanced their cytotoxicities, respectively.
