Yamaori Satoshi, Yamazaki Hiroshi, Iwano Shunsuke, Kiyotani Kazuma, Matsumura Keiko, Honda Goro, Nakagawa Kazuko, Ishizaki Takashi, Kamataki Tetsuya
Laboratory of Drug Metabolism, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo.
Drug Metab Pharmacokinet. 2004 Apr;19(2):120-9. doi: 10.2133/dmpk.19.120.
The purpose of this study was to evaluate a contribution of polymorphic cytochrome P450 (CYP) 3A5 to the oxidation of diltiazem, midazolam and testosterone by liver microsomes from Japanese subjects. Twenty-seven liver samples were classified into three groups according to the CYP3A5 genotypes; CYP3A5()1/()1 (n=3), ()1/()3 (n=12) and ()3/()3 (n=12). The results of genotyping and immunochemical quantitation of CYP3A5 protein showed a good accordance between the CYP3A5 genotype and CYP3A5 content but not CYP3A4 content in liver microsomes. The expression levels of hepatic CYP3A5 protein ranged from 20 to 60% of the sum of CYP3A4 and CYP3A5 contents in subjects with at least one wild type allele (()1). The CYP3A5 contents correlated well with liver microsomal activities of diltiazem N-demethylation, midazolam 1'- and 4-hydroxylations and testosterone 6beta-hydroxylation among subjects carrying at least one ()1 allele. In addition, the correlation coefficients of CYP3A5 contents with the rates of diltiazem N-demethylation, midazolam 1'-hydroxylation and testosterone 6beta- hydroxylation were higher than those of CYP3A4, although the value of CYP3A5 with the midazolam 4-hydroxylation rate was similar to that of CYP3A4. Kinetic analyses revealed a biphasic diltiazem N-demethylation in liver microsomes from subjects carrying the (*)1 allele. The apparent V(max)/K(m) values for recombinant CYP3A5 indicated the greater contributions to diltiazem N-demethylation and midazolam 1'-hydroxylation as compared with CYP3A4. These results suggest that polymorphic CYP3A5 contributes markedly to the drug oxidations, particularly diltiazem N-demethylation, midazolam 1'- hydroxylation and testosterone 6beta-hydroxylation by liver microsomes from Japanese subjects.
本研究的目的是评估多态性细胞色素P450（CYP）3A5对日本受试者肝脏微粒体中地尔硫卓、咪达唑仑和睾酮氧化的贡献。根据CYP3A5基因型，将27个肝脏样本分为三组；CYP3A5（）1/（）1（n = 3）、（）1/（）3（n = 12）和（）3/（）3（n = 12）。CYP3A5基因分型和免疫化学定量结果显示，肝脏微粒体中CYP3A5基因型与CYP3A5含量一致，但与CYP3A4含量不一致。在至少有一个野生型等位基因（）1的受试者中，肝脏CYP3A5蛋白的表达水平占CYP3A4和CYP3A5含量总和的20%至60%。在至少携带一个（）1等位基因的受试者中，CYP3A5含量与肝脏微粒体地尔硫卓N-去甲基化、咪达唑仑1'-和4-羟基化以及睾酮6β-羟基化活性密切相关。此外，CYP3A5含量与地尔硫卓N-去甲基化、咪达唑仑1'-羟基化和睾酮6β-羟基化速率的相关系数高于CYP3A4，尽管CYP3A5与咪达唑仑4-羟基化速率的值与CYP3A4相似。动力学分析显示，携带（*）1等位基因的受试者肝脏微粒体中地尔硫卓N-去甲基化呈双相性。重组CYP3A5的表观V（max）/K（m）值表明，与CYP3A4相比，其对地尔硫卓N-去甲基化和咪达唑仑1'-羟基化的贡献更大。这些结果表明，多态性CYP3A5对日本受试者肝脏微粒体的药物氧化有显著贡献，尤其是地尔硫卓N-去甲基化、咪达唑仑1'-羟基化和睾酮6β-羟基化。
