Cytochrome P-4502B6 is responsible for interindividual variability of propofol hydroxylation by human liver microsomes
Cytochrome P-4502B6 is responsible for interindividual variability of propofol hydroxylation by human liver microsomes
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DOI：
10.1097/00000542-200101000-00021
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发表时间：
2001-01-01
期刊：
影响因子：
8.8
通讯作者：
Greenblatt, DJ
中科院分区：
文献类型：
--
作者：
Court, MH;Duan, SX;Greenblatt, DJ
背景：异丙酚氧化为4-羟基异丙酚代表了这种麻醉剂在人体代谢中的一个重要途径。本研究的目的是鉴定介导这种生物转化的主要细胞色素P-450 （CYP）亚型。方法：利用人肝微粒体和cdna表达的CYPs检测异丙酚羟基化活性和酶动力学。肝脏微粒体中CYP2B6特异性标记活性和CYP2B6蛋白含量也被量化以进行相关分析。最后，用抑制抗体确定CYPs对肝微粒体异丙酚羟基化的相对贡献。结果：肝微粒体异丙酚羟基化具有19倍以上的差异性，且与CYP2B6蛋白含量（r = 0.904）、CYP2B6标志物活性、s -甲苯托因n -去甲基化（r = 0.919）和安非他酮羟基化（r = 0.854）密切相关。高活性和中活性肝脏表现出高亲和酶动力学（K-m < 8 M），而低活性肝脏表现出低亲和酶动力学（K-m bb0 80 muM）。所有评估的CYPs都能够羟基化异丙酚；其中，CYP2B6和CYP2C9活性最强。动力学分析表明CYP2B6是一种高亲和力（K-m = 10 +/- 2 muM，平均估计的+/- SE）的高容量酶，而CYP2C9是一种低亲和力（K-m = 41 +/- 8 muM）的高容量酶。此外，与CYP2C亚型（16 +/- 7%抑制）相比，免疫抑制显示CYP2B6对肝微粒体活性的贡献更大（56 +/- 22%抑制；平均+/- SD）。结论：细胞色素P-450 2B6和较小程度的CYP2C9参与异丙酚的氧化代谢。然而，CYP2B6是人肝微粒体对该药物羟基化的个体间差异性的主要决定因素。
Background: Oxidation of propofol to 4-hydroxypropofol represents a significant pathway in the metabolism of this anesthetic agent in humans. The aim of this study was to identify the principal cytochrome P-450 (CYP) isoforms mediating this biotransformation.Methods: Propofol hydroxylation activities and enzyme kinetics mere determined using human liver microsomes and cDNA-expressed CYPs. CYP-specific marker activities and CYP2B6 protein content were also quantified in hepatic microsomes for correlational analyses. Finally, inhibitory antibodies were used to ascertain the relative contribution of CYPs to propofol hydroxylation by hepatic microsomes.Results: Propofol hydroxylation by hepatic microsomes showed more than 19-fold variability and was most closely correlated to CYP2B6 protein content (r = 0.904), and the CYP2B6 marker activities, S-mephenytoin N-demethylation (r = 0.919) and bupropion hydroxylation (r = 0.854). High- and intermediate-activity livers demonstrated high-affinity enzyme kinetics (K-m < 8 M), whereas low-activity livers displayed low-affinity kinetics (K-m > 80 muM). All of the CYPs evaluated were capable of hydroxylating propofol; however, CYP2B6 and CYP2C9 were most active. Kinetic analysis indicated that CYP2B6 is a high-affinity (K-m = 10 +/- 2 muM; mean +/- SE of the estimate), high-capacity enzyme, whereas CYP2C9 is a low-affinity (K-m = 41 +/- 8 muM), high-capacity enzyme. Furthermore, immunoinhibition showed a greater contribution of CYP2B6 (56 +/- 22% inhibition; mean +/- SD) compared with CYP2C isoforms (16 +/- 7% inhibition) to hepatic microsomal activity.Conclusions: Cytochrome P-450 2B6, and to a lesser extent CYP2C9, contribute to the oxidative metabolism of propofol. However, CYP2B6 is the principal determinant of interindividual variability in the hydroxylation of this drug by human liver microsomes.