Colby H D, Purcell H, Kominami S, Takemori S, Kossor D C
Department of Pharmacology and Toxicology, Philadelphia College of Pharmacy and Science, PA 19104.
Toxicology. 1994 Nov-Dec;94(1-3):31-40. doi: 10.1016/0300-483x(94)90026-4.
Previous investigations demonstrated that carbon tetrachloride (CCl4) was activated by adrenal microsomes, resulting in various functional changes and ultimately in necrosis of the zona reticularis of the gland. Experiments were done to identify the adrenal P450 isozyme(s) involved in the bioactivation of CCl4. Incubation of microsomes from the zona reticularis (ZR) of the guinea pig adrenal cortex with CCl4 plus NADPH caused initiation of lipid peroxidation, covalent binding of CCl4-derived radioactivity to protein, and degradation of cytochrome(s) P450. Preincubation of the microsomal preparations with inhibitory antibodies to P450(17 alpha) or P450C21 decreased the corresponding enzyme activities (17 alpha-hydroxylation and 21-hydroxylation), but did not affect the activation of CCl4. 1-Aminobenzotriazole (ABT), a suicide inhibitor of some P450 isozymes, decreased the enzyme activities catalysed by an adrenal 52,000 Da (52 kDa) isozyme, but had no effect on the function of P450(17 alpha) or P450C21. However, ABT completely inhibited the CCl4-induced LP and covalent binding in adrenal microsomes. The results indicate that adrenal CCl4 activation is catalysed by the 52 kDa P450 isozyme and not by the steroid hydroxylases. Localization of the 52 kDa isozyme to the ZR probably accounts for the selective necrosis of this region of the gland by CCl4.
先前的研究表明，四氯化碳（CCl4）可被肾上腺微粒体激活，导致各种功能变化，最终引起肾上腺网状带坏死。进行实验以鉴定参与CCl4生物激活的肾上腺P450同工酶。将豚鼠肾上腺皮质网状带（ZR）的微粒体与CCl4加NADPH一起孵育，会引发脂质过氧化、CCl4衍生的放射性与蛋白质的共价结合以及细胞色素P450的降解。用针对P450（17α）或P450C21的抑制性抗体对微粒体制剂进行预孵育，会降低相应的酶活性（17α-羟化和21-羟化），但不影响CCl4的激活。1-氨基苯并三唑（ABT）是某些P450同工酶的自杀性抑制剂，可降低由肾上腺52,000 Da（52 kDa）同工酶催化的酶活性，但对P450（17α）或P450C21的功能没有影响。然而，ABT完全抑制了CCl4诱导的肾上腺微粒体中的脂质过氧化和共价结合。结果表明，肾上腺CCl4激活是由52 kDa的P450同工酶催化的，而不是由类固醇羟化酶催化的。52 kDa同工酶在ZR中的定位可能解释了CCl4对该肾上腺区域的选择性坏死。
