罗格列酮对大鼠肝细胞色素P450 3A活性的影响

[目的]探讨罗格列酮对细胞色素P4503A活性的影响。[方法]在正常大鼠肝细胞微粒体中加入浓度为0，0.1,0.25,0.5,1.0mmol/L罗格列酮，以红霉素为底物，测定细胞色素P4503A活性。[结果]加入不同浓度罗格列酮的大鼠肝微粒体中细胞色素P4503A活性无显著性差异。[结论]罗格列酮对大鼠的肝细胞色素P4503A活性无明显影响。     

大鼠肝微粒体细胞色素P450酶系检测方法学研究

目的 :建立大鼠肝微粒体蛋白含量以及肝微粒体细胞色素P4 5 0酶系含量与活性测定的紫外和荧光分光光度方法。方法 :应用差速离心法提取大鼠肝微粒体 ,Lowery法测定肝微粒体蛋白浓度 ,应用紫外和荧光分光光度法测定肝微粒体细胞色素P4 5 0酶系含量及活性。结果 :牛血清白蛋白标准曲线的线性范围为 2 5～ 2 5 0mg·L-1,最低检测限为2 5mg·L-1,相关系数r为 0 .9975 ;紫外分光光度法测定细胞色素P4 5 0和细胞色素b5含量及NADPH CytC还原酶活性的结果显示方法灵敏 ;测定氨基比林N 脱甲基酶、红霉素N 脱甲基酶活性的甲醛标准曲线 ,线性范围为 0 .0 5～ 0 .5mmol·L-1,最低检测限为 0 .0 5mmol·L-1,相关系数r为 0 .9988;测定 7 乙氧基香豆素脱烃酶活性的resorufin标准曲线线性范围为 1～ 8μmol·L-1,最低检测限为 1μmol·L-1,相关系数r为 0 .9998。结论 :紫外和荧光分光光度方法测定大鼠肝微粒体细胞色素P4 5 0酶系中 6种酶的含量及活性的灵敏可靠 ,重复性较好。     

雷公藤甲素单次及多次给药对大鼠肝药酶活性的影响

目的:研究雷公藤甲素对大鼠肝药酶活性的影响。方法:对SD大鼠以雷公藤甲素(150、300、450μg·kg-1)灌胃给药,每天1次,给药1d或14d,分别测定细胞色素P450、细胞色素b5含量及红霉素N-去甲基酶(ERD)、二甲基亚硝胺脱甲基酶(NDMA)、甲氧基异唑脱甲基酶(MROD)、乙氧基异唑脱乙基酶(EROD)和戊氧基异唑脱烷基酶(PROD)活性;CYP3A和CYP2E1蛋白含量采用Westernblotting法分析。结果:单次灌胃雷公藤甲素对肝药酶活性及CYP2E1、CYP3A蛋白表达基本无影响;多次给予雷公藤甲素(450μg·kg-1,14d)能诱导NDMA活性,抑制ERD活性,轻度升高CYP2E1蛋白表达,显著降低CYP3A蛋白表达。结论:长期较高剂量给予雷公藤甲素能抑制CYP3A活性,轻度诱导CYP2E1活性。     

胶原夹心培养大鼠肝细胞及其细胞色素P450酶活性的测定

目的　自制大鼠尾腱Ⅰ型胶原培养原代大鼠肝细胞 ,测定肝细胞中细胞色素P450 (cytochromeP450 ,CYP)酶活性。方法　制备无菌大鼠尾腱Ⅰ型胶原 ,比较单层胶原铺底法 (collagencoated ,CC)及胶原夹心法 (collagensandwichsys tem ,CSS)培养大鼠肝细胞的生长及功能维持情况。CSS法培养肝细胞 ,分别加入泼尼松龙 (10 0 μmol·L- 1,3d)、尼莫地平 (50 μmol·L- 1,2d)和利福平 (50 μmol·L- 1,2d) ,测定CYP1A、CYP2E1及CYP3A酶活性。结果　CSS法培养 6d后 ,肝细胞生长良好。CC法培养 3d后细胞开始脱落 ,此后持续增多 ;6d后 ,培养上清液中ALT、AST与LDH活性升高 ,均高于同期CSS法培养细胞上清液中的水平。加入经CYP3A代谢药物 ,CSS培养肝细胞CYP1A活性无明显改变 ;尼莫地平使CYP3A活性升高 3 3 % ,而CYP2E1活性下降 45% (P <0 0 5) ;利福平使CYP3A活性升高为对照组的1 94倍 (P <0 0 5) ,对CYP2E1活性无作用。结论　同为CYP3A底物 ,泼尼松龙、尼莫地平和利福平对CYP亚型的影响不同 ,但不改变肝细胞CYP1A对致癌物的活化。CSS培养法可作为体外模型用于药物代谢研究     

辛伐他汀对大鼠肝微粒体药物代谢酶活性的影响

目的研究辛伐他汀(simvastatin, SV)对大鼠肝脏药物代谢酶活性的影响。方法大鼠口服给予SV,qd×7,超速离心法分离肝微粒体,一氧化碳示差光谱法测定细胞色素P450(CYP)含量,以红霉素、苯胺、CDNB、利尿酸、7-羟基-4-甲基香豆素和对羟基联苯为底物分别测定肝微粒体红霉素脱甲基酶(CYP3A4)、苯胺羟化酶(CYP2E1)、谷胱甘肽-S-转移酶(glutathione S transferase, GST)及其π亚型 (πGST)、尿苷二磷酸葡萄糖醛酸转移酶(uridine diphosphoglucuronyl transferase, UGT1和UGT2)活性。结果大鼠口服给予SV可明显降低大鼠肝微粒体CYP含量及CYP3A4活性,对CYP2E1则没有显明影响。同时,SV 则可显著增高大鼠肝微粒体GST、πGST及UGT1和UGT2活性。结论SV可降低大鼠肝微粒体CYP3A4活性,而增高肝微粒体Ⅱ相代谢酶的活性。     

辛伐他汀对大鼠肝微粒体药物代谢酶活性的影响

目的 研究辛伐他汀(simvastatin, SV)对大鼠肝脏药物代谢酶活性的影响。方法 大鼠口服给予SV,qd×7,超速离心法分离肝微粒体,一氧化碳示差光谱法测定细胞色素P450(CYP)含量,以红霉素、苯胺、CDNB、利尿酸、7-羟基-4-甲基香豆素和对羟基联苯为底物分别测定肝微粒体红霉素脱甲基酶(CYP3A4)、苯胺羟化酶(CYP2E1)、谷胱甘肽-S-转移酶(glutathione S transferase, GST)及其π亚型 (πGST)、尿苷二磷酸葡萄糖醛酸转移酶(uridine diphosphoglucuronyl transferase, UGT1和UGT2)活性。结果 大鼠口服给予SV可明显降低大鼠肝微粒体CYP含量及CYP3A4活性,对CYP2E1则没有显明影响。同时,SV 则可显著增高大鼠肝微粒体GST、πGST及UGT1和UGT2活性。结论 SV可降低大鼠肝微粒体CYP3A4活性,而增高肝微粒体Ⅱ相代谢酶的活性。     

丹红注射液对大鼠肝微粒体5种CYP亚型酶活性的影响

摘要目的研究丹红注射液对5种细胞色素P450亚型酶活性的影响,为临床合理用药提供参考。方法采用大鼠体外肝微粒体孵育法,分别以非那西丁、甲苯磺丁脲、右美沙芬、氯唑沙宗、睾酮为CYP1A2、CYP2C9、CYP2D6、CYP2E1、CYP3A4的探针药物,在大鼠肝微粒体孵育体系中孵育,用高效液相色谱（HPLC）法测定相应的代谢产物,比较空白对照组和丹红注射液低、中、高剂量组之间探针药物代谢率的差异,评价丹红注射液对各亚型酶活性的影响。结果在体外肝微粒体孵育体系中,丹红注射液低剂量组中CYP1A2 和CYP2C9活性与空白对照组相比,差异无统计学意义（P＞0.05）;中和高剂量组中CYP1A2和CYP2C9活性与空白对照组相比降低,差异有统计学意义（P＜0.05或P＜0.01）;丹红注射液低、中、高剂量组中CYP2D6、CYP2E1、CYP3A4的活性与空白对照组相比,差异无统计学意义（P＞0.05）。丹红注射液对大鼠肝微粒体CYP1A2酶活性的半数抑制浓度（IC50）和抑制常数（Ki）分别为0.54%和0.226%。结论丹红注射液对大鼠肝微粒体CYP1A2酶活性有抑制作用,且为混合型抑制;对CYP2C9有弱抑制作用;对CYP2D6、CYP2E1、CYP3A4酶活性无明显影响。     

氟喹诺酮类药对人肝药酶活性的影响

目的 :观察氟喹诺酮类 (FQs)药物对人肝微粒体药物代谢酶 (细胞色素P 4 5 0 )活性影响的差异。方法 :反应体系中微粒体蛋白终浓度为 0 .33～2 .0 g·L- 1,药物终浓度为 4 0 0mg·L- 1,测定药物代谢酶的活性。对照不加药。并测定不同底物浓度和不同环丙沙星浓度时乙基吗啡N 脱甲基酶的Vm和Km 值 ,求抑制常数Ki。结果 :FQs对酶活性的抑制强度为 :培氟沙星 (PFLX) >环丙沙星 (CPLX)>氧氟沙星 (OFLX) >左氧氟沙星 (LVLX)。FQs对戊巴比妥侧链羟化酶 (PSCH )、苯并芘羟化酶(BPH)、氨基比林N 脱甲基酶 (ADM )、乙基吗啡N 脱甲基酶 (EDM )和NADPH 细胞色素C还原酶的平均被抑制率分别为 :2 9% ,2 6 % ,19% ,17%和2 .3%。CPLX对EDM的抑制为竞争性抑制为主的混合性抑制 ,抑制常数Ki=2 5 0mg·L- 1。结论 :4种FQs对多种肝药酶活性均有不同程度的抑制 ,LVLX的抑制作用相对较弱。 5种肝药酶对药物的敏感性也各不相同。CPLX对EDM的抑制是竞争性抑制为主的混合性抑制。     

罗格列酮对高脂血症大鼠的胰岛素抵抗作用及其机制研究

目的 :研究罗格列酮及格列齐特对高脂血症大鼠胰岛素抵抗的改善作用及其机制。方法 :建立高脂血症大鼠胰岛素抵抗模型 ,并将其分为模型组、罗格列酮组和格列齐特组 ,观察罗格列酮和格列齐特对其糖耐量减退、血清血糖血脂、TNF α、Fins含量、肝细胞TG含量、脂质过氧化和肝肾功能等的影响。结果 :罗格列酮和格列齐特均有可能改善高脂血症致胰岛素抵抗模型病鼠的IGT状态 ,给药 2h后不同程度地降低病鼠FSG及TNF α浓度 (P <0 .0 5 ) ,显著降低病鼠肝组织中TG含量 (P <0 .0 1) ,明显抑制MDA产生 (P <0 .0 1)及增强GSH贮量作用 (P <0 .0 1)。罗格列酮还可降低病鼠高胰岛素水平及Fins浓度 (P <0 .0 1) ,明显降低病鼠BUN和Cr含量 (P <0 .0 5 ) ,提高ISI(P <0 .0 1)及增强SOD活性 (P <0 .0 5 )。结论 :罗格列酮能改善高脂饲养引发的胰岛素抵抗。     

HPLC测定大鼠肝微粒体P450活性方法学研究进展

近年来，越来越多的研究者意识到使用肝微粒体进行细胞色素P450活性测定的重要性。本文综述了应用高效液相色谱进行大鼠肝微粒体P450活性测定的方法学研究进展，内容包括肝微粒体的制备方法，细胞色素P450代谢酶系的特异性底物及其代谢产物和使用高效液相色谱进行细胞色素P450活性测定的应用条件。     

Characterization of the cytochrome P450 enzymes involved in the in vitro metabolism of rosiglitazone

AIMS: To identify the human cytochrome P450 enzyme(s) involved in the in vitro metabolism of rosiglitazone, a potential oral antidiabetic agent for the treatment of type 2 diabetes-mellitus. Method The specific P450 enzymes involved in the metabolism of rosiglitazone were determined by a combination of three approaches; multiple regression analysis of the rates of metabolism of rosiglitazone in human liver microsomes against selective P450 substrates, the effect of selective chemical inhibitors on rosiglitazone metabolism and the capability of expressed P450 enzymes to mediate the major metabolic routes of rosiglitazone metabolism. Result The major products of metabolism following incubation of rosiglitazone with human liver microsomes were para-hydroxy and N-desmethyl rosiglitazone. The rate of formation varied over 38-fold in the 47 human livers investigated and correlated with paclitaxel 6alpha-hydroxylation (P<0.001). Formation of these metabolites was inhibited significantly (>50%) by 13-cis retinoic acid, a CYP2C8 inhibitor, but not by furafylline, quinidine or ketoconazole. In addition, both metabolites were produced by microsomes derived from a cell line transfected with human CYP2C8 cDNA. There was some evidence for CYP2C9 playing a minor role in the metabolism of rosiglitazone. Sulphaphenazole caused limited inhibition (<30%) of both pathways in human liver microsomes and microsomes from cells transfected with CYP2C9 cDNA were able to mediate the metabolism of rosiglitazone, in particular the N-demethylation pathway, albeit at a much slower rate than CYP2C8. Rosiglitazone caused moderate inhibition of paclitaxel 6alpha-hydroxylase activity (CYP2C8; IC50=18 microm ), weak inhibition of tolbutamide hydroxylase activity (CYP2C9; IC50=50 microm ), but caused no marked inhibition of the other cytochrome P450 activities investigated (CYP1A2, 2A6, 2C9, 2C19, 2D6, 2E1, 3A and 4A). Conclusion CYP2C8 is primarily responsible for the hydroxylation and N-demethylation of rosiglitazone in human liver; with minor contributions from CYP2C9.     

淫羊藿总黄酮对大鼠肝微粒体CYP1A2、CYP3A4和CYP2E1活性的影响

评估淫羊藿总黄酮对大鼠肝细胞色素P450及其主要亚型活性的潜在影响。淫羊藿总黄酮以300mg／kg／d的剂量对SD大鼠进行连续灌胃处理15天，测定肝微粒体中cYP450含量与CYP1A2、CYP3A4和CYP2E1亚型活性，观察淫羊藿总黄酮的效应。CYP1A2的活性用荧光比色法进行测定，CYP3A4和CYP2E1的活性用紫外可见分光光度法测定。淫羊藿总黄酮处理后的大鼠肝脏CYP450含量及CYP1A2、CYP3A4和CYP2E1亚型活性均明显增高，其中CYP1A2和CYP2E1活性升高显著（P〈0．01）。淫羊藿总黄酮对大鼠肝脏CYP450及主要亚型CYP1A2、CYP3A4和CYP2E1活性均有诱导效应。     

新型Hsp90抑制剂——SNX-2112对大鼠肝药酶活性的影响

目的研究SNX-2112注射液对大鼠肝药酶活性的影响。方法大鼠分为苯巴比妥钠诱导组、CCl4抑制组、SNX-2112高、中、低(10、5、2.5mg·kg-1)剂量组、生理盐水对照组、空白溶媒组。用紫外分光光度法测定了SNX-2112注射液对大鼠肝脏系数、CYP450含量以及甲醛生成速率的影响。结果3种剂量SNX-2112对大鼠肝脏系数以及蛋白含量的影响都不明显,但均能抑制CYP450含量。从甲醛生成速率结果看,高、中两种剂量SNX-2112均能抑制大鼠氨基比林-N-脱甲基酶活性及红霉素-N-脱甲基酶活性,而低剂量对其影响不明显。结论SNX-2112注射液在高浓度对大鼠肝药酶CYP3A和CYP2E1亚型活性有抑制作用。     

Cytochrome p450-dependent metabolism of trichloroethylene in rat kidney.

The metabolism of trichloroethylene (Tri) by cytochrome P450 (P450) was studied in microsomes from liver and kidney homogenates and from isolated renal proximal tubular (PT) and distal tubular (DT) cells from male Fischer 344 rats. Chloral hydrate (CH) was the only metabolite consistently detected and was used as a measurement of P450-dependent metabolism of Tri. Pretreatment of rats with pyridine increased CH formation in both liver and kidney microsomes, whereas pretreatment of rats with clofibrate increased CH formation only in kidney microsomes. Pyridine increased CYP2E1 expression in both liver and kidney microsomes, whereas clofibrate had no effect on hepatic but increased renal CYP2E1 and CYP2C11 protein levels. These results suggest a role for CYP2E1 in both the hepatic and renal metabolism of Tri and a role for CYP2C11 in the renal metabolism of Tri. Studies with the general P450 inhibitor SKF-525A and the CYP2E1 competitive substrate chlorzoxazone provided additional support for the role of CYP2E1 in both tissues. CH formation was higher in PT cells than in DT cells and was time and reduced nicotinamide adenine dinucleotide phosphate (NADPH) dependent. However, pretreatment of rats with either pyridine or clofibrate had no effect on CYP2E1 or CYP2C11 protein levels or on CH formation in isolated cells. These data show for the first time that Tri can be metabolized to at least one of its P450 metabolites in the kidneys and quantitate the effect of P450 induction on Tri metabolism in the rat kidney.     

Oxidation of 1,8-cineole, the monoterpene cyclic ether originated from eucalyptus polybractea, by cytochrome P450 3A enzymes in rat and human liver microsomes.

1,8-Cineole, the monoterpene cyclic ether known as eucalyptol, is one of the components in essential oils from Eucalyptus polybractea. We investigated the metabolism of 1,8-cineole by liver microsomes of rats and humans and by recombinant cytochrome P450 (P450 or CYP) enzymes in insect cells in which human P450 and NADPH-P450 reductase cDNAs had been introduced. 1,8-Cineole was found to be oxidized at high rates to 2-exo-hydroxy-1,8-cineole by rat and human liver microsomal P450 enzymes. In rats, pregenolone-16alpha-carbonitrile (PCN) and phenobarbital induced the 1,8-cineole 2-hydroxylation activities by liver microsomes. Several lines of evidence suggested that CYP3A4 is a major enzyme involved in the oxidation of 1,8-cineole by human liver microsomes: (1), 1,8-cineole 2-hydroxylation activities by liver microsomes were inhibited very significantly by ketoconazole, a CYP3A inhibitor, and anti-CYP3A4 immunoglobulin G; (2), there was a good correlation between CYP3A4 contents and 1,8-cineole 2-hydroxylation activities in liver microsomes of eighteen human samples; and (3), of various recombinant human P450 enzymes examined, CYP3A4 had the highest activities for 1,8-cineole 2-hydroxylation; the rate catalyzed by CYP3A5 was about one-fourth of that catalyzed by CYP3A4. Kinetic analysis showed that K(m) and V(max) values for the oxidation of 1,8-cineole by liver microsomes of human sample HL-104 and rats treated with PCN were 50 microM and 91 nmol/min/nmol P450 and 20 microM and 12 nmol/min/nmol P450, respectively. The rates observed using human liver microsomes and recombinant CYP3A4 were very high among other CYP3A4 substrates reported so far. These results suggest that 1,8-cineole, a monoterpenoid present in nature, is one of the effective substrates for CYP3A enzymes in rat and human liver microsomes.     

Roles of human CYP2A6 and rat CYP2B1 in the oxidation of (+)-fenchol by liver microsomes

The metabolism of (+)-fenchol was investigated in vitro using liver microsomes of rats and humans and recombinant cytochrome P450 (P450 or CYP) enzymes in insect cells in which human/rat P450 and NADPH-P450 reductase cDNAs had been introduced. The biotransformation of (+)-fenchol was investigated by gas chromatography-mass spectrometry (GC-MS). (+)-Fenchol was oxidized to fenchone by human liver microsomal P450 enzymes. The formation of metabolites was determined by the relative abundance of mass fragments and retention times on GC. Several lines of evidence suggested that CYP2A6 is a major enzyme involved in the oxidation of (+)-fenchol by human liver microsomes. (+)-Fenchol oxidation activities by liver microsomes were very significantly inhibited by (+)-menthofuran, a CYP2A6 inhibitor, and anti-CYP2A6. There was a good correlation between CYP2A6 contents and (+)-fenchol oxidation activities in liver microsomes of ten human samples. Kinetic analysis showed that the Vmax/Km values for (+)-fenchol catalysed by liver microsomes of human sample HG03 were 7.25 nM-1 min-1. Human recombinant CYP2A6-catalyzed (+)-fenchol oxidation with a Vmax value of 6.96 nmol min-1 nmol-1 P450 and apparent Km value of 0.09 mM. In contrast, rat CYP2A1 did not catalyse (+)-fenchol oxidation. In the rat (+)-fenchol was oxidized to fenchone, 6-exo-hydroxyfenchol and 10-hydroxyfenchol by liver microsomes of phenobarbital-treated rats. Recombinant rat CYP2B1 catalysed (+)-fenchol oxidation. Kinetic analysis showed that the Km values for the formation of fenchone, 6-exo- hydroxyfenchol and 10-hydroxyfenchol in rats treated with phenobarbital were 0.06, 0.03 and 0.03 mM, and Vmax values were 2.94, 6.1 and 13.8 nmol min-1 nmol-1 P450, respectively. Taken collectively, the results suggest that human CYP2A6 and rat CYP2B1 are the major enzymes involved in the metabolism of (+)-fenchol by liver microsomes and that there are species-related differences in the human and rat CYP2A enzymes.     

Induction of CYP1A1 and CYP2E1 in rat liver by histamine: binding and kinetic studies

Histamine (HA) may bind to cytochrome P450 (CYP450) in rat liver microsomes. The CYP450-HA complex seems to regulate some cellular processes such as proliferation. In the present work, it is shown that HA increases the activity and protein level of CYP1A1 and CYP2E1, in vivo. CYP1A1 is associated with polycyclic aromatic hydrocarbon-mediated carcinogenesis and CYP2E1 with liver damage by oxidative stress. Studies of enzyme kinetics and binding with rat liver microsomes and supersomes were carried out to determine whether HA is a substrate of CYP1A1 and/or CYP2E1. The lack of NADPH oxidation in the presence of HA showed that it is not a substrate for CYP1A1. Activity measurements using the O-dealkylation of ethoxyresorufin indicated that HA is a mixed-type inhibitor of CYP1A1 in both microsomes and supersomes. On the other hand, HA induced a significant NADPH oxidation catalyzed by CYP2E1 supersomes, strongly suggesting that HA is a substrate for this isoform. Furthermore, HA is consumed in the presence of CYP2E1-induced microsomes and supersomes, as determined by o-phtalaldehyde complexes with HA by HPLC. The present findings may contribute to understand better the physiological function of CYP450 in relation with inflammation and other physiological processes in which HA may have a relevant role.     

Rat cytochrome P450 2C11 in liver microsomes involved in oxidation of anesthetic agent propofol and deactivated by prior treatment with propofol.

Propofol (2,6-diisopropylphenol) is a widely-used anesthetic agent attributable to its rapid biotransformation. Liver microsomal cytochrome P450 (P450) isoforms involved in the biotransformation of propofol in rats and the effects of propofol in vivo on P450 levels in rats were investigated. Of six cDNA-expressed rat P450 isoforms tested, CYP2B1 and CYP2C11 had high catalytic activities from 5 microM and 20 microM propofol concentrations, respectively. Rates of propofol metabolism, at a substrate concentration of 20 microM based on the reported human blood concentration, were decreased by intraperitoneal treatment of propofol with male rats, in contrast to a strong induction by phenobarbital. Single intravenously administered propofol (10 mg/kg) caused the decrease of total P450 and CYP2C contents and activities of testosterone 16alpha-hydroxylation and propofol metabolism in liver microsomes from male rats. The suppressive effects were caused by administered propofol (10 mg/kg) twice every 4 h on CYP2B activities such as testosterone 16beta-hydroxylation or pentoxyresorufin O-depentylation, in addition to the strong suppression of CYP2C function by the single propofol treatment. These results suggest that CYP2C11, presumably deactivated by propofol, has an important role in propofol metabolism in rat liver microsomes. Repeated administration of propofol could markedly decrease the biotransformation of propofol via P450 deactivation.     

Behavioral and immunohistological assessment of painful neuropathy induced by a single oxaliplatin injection in the rat

The in vitro metabolism of permethrin and its hydrolysis products in rats was investigated. Cis- and trans-permethrin were mainly hydrolyzed by liver microsomes, and also by small-intestinal microsomes of rats. trans-Permethrin was much more effectively hydrolyzed than the cis-isomer. When NADPH was added to the incubation mixture of the liver microsomes, three metabolites, 3-phenoxybenzyl alcohol (PBAlc), 3-phenoxybenzaldehyde (PBAld) and 3-phenoxybenzoic acid (PBAcid), were formed. However, only PBAlc was formed by rat liver microsomes in the absence of cofactors. The microsomal activities of rat liver and small intestine were inhibited by bis-p-nitrophenyl phosphate, an inhibitor of carboxylesterase (CES). ES-3 and ES-10, isoforms of the CES 1 family, exhibited significant hydrolytic activities toward trans-permethrin. When PBAlc was incubated with rat liver microsomes in the presence of NADPH, PBAld and PBAcid were formed. The NADPH-linked oxidizing activity was inhibited by SKF 525-A. Rat recombinant cytochrome P450, CYP 2C6 and 3A1, exhibited significant oxidase activities with NADPH. When PBAld was incubated with the microsomes in the presence of NADPH, PBAcid was formed. CYP 1A2, 2B1, 2C6, 2D1 and 3A1 exhibited significant oxidase activities in this reaction. Thus, permethrin was hydrolyzed by CES, and PBAlc formed was oxidized to PBAld and PBAcid by the cytochrome P450 system in rats.     

大黄素对大鼠肝脏CYP450酶的诱导研究

目的 探讨大黄素对大鼠肝脏细胞色素P450酶(CYP450)及其主要亚型的影响。方法 20只雄性SD大鼠, 随机分成4组, 每组5只, 分别为溶剂对照组, 170、500和1 500 mg/kg大黄素染毒组, 大黄素蒸馏水混悬后连续经口给药16 d, 结束后次日取大鼠肝脏组织制作微粒体, 分别采用CO还原差示光谱法、分光光度法及化学发光法检测大鼠肝脏微粒体总CYP450水平, 红霉素脱甲基酶(CYP3A)、氨基比啉-N-脱甲基酶, CYP1A、CYP2B和CYP2E1酶活性变化。结果 大黄素连续经口给药16 d, 能够引起大鼠肝脏微粒体总CYP450显著升高、可轻度诱导CYP3A、CYP1A、CYP2E1和CYP2B酶, 500 mg/kg剂量组最明显。结论 大黄素对大鼠肝脏中CYP3A、CYP1A、CYP2B和CYP2E1酶均有诱导作用。