【摘要翻译】离体大鼠肝脏灌流时短期抑制NO对CYP介导的药物代谢的影响：时间依赖及可逆性
【文题】：SHORT-TERM INHIBITORY EFFECTS OF NITRIC OXIDE ON CYTOCHROME P450-MEDIATED DRUG METABOLISM: TIME DEPENDENCY AND REVERSIBILITY PROFILES IN ISOLATED PERFUSED RAT LIVERS
【作者】：Ragini Vuppugalla and Reza Mehvar
【单位】：School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas
【杂志】：Drug Metab Dispos 2004 Dec 32: 1446-1454.
【摘要】：
Nitric oxide (NO) is implicated as a mediator in the decreased catalytic activities of cytochrome P450 (P450) enzymes during inflammation or infection. Here, we examined the time course and the reversibility of the NO effect on P450s using isolated perfused rat livers. Livers were perfused at a constant rate with the NO donor sodium nitroprusside (SNP) for 0.5 or 1 h, followed by washout periods of 0 to 2.5 h. At the end of perfusion, microsomes were prepared and analyzed for P450 activities and other metabolic markers. Whereas 0.5 h of NO exposure caused an irreversible decline (30%) in total P450 content, a greater decline after 1 h of NO (55%) was mostly (30%) reversible, a pattern identical to that observed for the microsomal heme content. NO exposure also caused an enzyme-selective and time-dependent decline in P450 activities. Whereas the pattern of decline and reversibility of activities were qualitatively similar for CYP3A2, 2C11, 2E1, and 1A1/2, they differed for 2B1/2 and 2D1 in that the decline in the activity was delayed (1 h) for 2B1/2 and not observed for 2D1. This may be attributed to the accessibility of heme or cysteine thiolate and/or the presence/reactivity of critical cysteinyl amino acid residues in various P450 enzymes. Additionally, for most enzymes, the activity showed a biphasic decline, one within 1 h of SNP perfusion and another after 2 h of washout. This was associated with an identical biphasic decline in the microsomal free thiols, presumably due to the rapid and slow reaction of NO and peroxynitrite, respectively, with critical P450 thiols. The short-term effects of NO on P450 are time-dependent and enzyme-selective, with both reversible and irreversible mechanisms.
【翻译】：一氧化氮NO被认为是在感染和炎症中介导CYP450催化活性下降的中间体。此文中，我们在离体灌注的大鼠肝脏模型上观察了NO对P450在时间和可逆性两方面的影响。肝脏用一氧化氮给予体-硝普钠（SNP）恒速灌注0.5或1小时，然后冲洗0-2.5小时。灌注结束后，制备微粒体并进行P450活性以及其他代谢指标的分析。虽然0.5小时NO暴露能使约30%CYP（相对于总含量）不可逆下降，但是一小时NO的暴露能使70%CYP（相对于总含量）不可逆下降。微粒体亚铁血红素的含量的改变与之相一致的。NO的暴露也能使CYP酶活性的选择性和时间依赖性降低。这种下降的方式和活性的不可逆性与CYP3A2, 2C11, 2E1, 1A1/2的含量是一致的，但是2B1/2 和 2D1却不同，因为前者(2B1/2)活性的下降是较滞后的（1h）而后者(2D1)活性却没有改变。这种现象的产生可能是由于各种CYP酶中心血红素的可接近性或者是半胱氨酸巯基的暴露及半胱酰氨主要残基的可反应性相关。此外，对于大部分的酶都具有二次活性降低，首次降低在SNP灌注的1小时内，再次降低是冲洗2小时后。这与线粒体的自由巯基的减少是一致的，其也存在二次减少，进而推测可能分别由于NO的快速反应及过(氧化)亚硝酸盐的迟发反应造成的。短期NO对CYP的影响是时间依赖性和酶选择性的，二者具有可逆和不可逆的机制。
【评论】：首次阐述了NO短期对于CYP的影响。离体大鼠肝脏灌流模型时研究短期NO对CYP影响的理想模型。同时可以进一步考虑给予NO选择性抑制剂（抑制CYP酶活性的降低）或制作病理模型在此基础上观测NO对CYP的影响。
附全文
Vuppugalla R, Mehvar R.
Short-term inhibitory effects of nitric oxide on cytochrome P450-mediated drug metabolism: time dependency and reversibility profiles in isolated perfused rat livers.
Drug Metab Dispos. 2004 Dec;32(12):1446-54. Epub 2004 Dec.
PMID: 15383494
PART 1
2.part1.rar(195.31k)
PART 2
2.part2.rar(125.9k)
【文题】：SHORT-TERM INHIBITORY EFFECTS OF NITRIC OXIDE ON CYTOCHROME P450-MEDIATED DRUG METABOLISM: TIME DEPENDENCY AND REVERSIBILITY PROFILES IN ISOLATED PERFUSED RAT LIVERS
【作者】：Ragini Vuppugalla and Reza Mehvar
【单位】：School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas
【杂志】：Drug Metab Dispos 2004 Dec 32: 1446-1454.
【摘要】：
Nitric oxide (NO) is implicated as a mediator in the decreased catalytic activities of cytochrome P450 (P450) enzymes during inflammation or infection. Here, we examined the time course and the reversibility of the NO effect on P450s using isolated perfused rat livers. Livers were perfused at a constant rate with the NO donor sodium nitroprusside (SNP) for 0.5 or 1 h, followed by washout periods of 0 to 2.5 h. At the end of perfusion, microsomes were prepared and analyzed for P450 activities and other metabolic markers. Whereas 0.5 h of NO exposure caused an irreversible decline (30%) in total P450 content, a greater decline after 1 h of NO (55%) was mostly (30%) reversible, a pattern identical to that observed for the microsomal heme content. NO exposure also caused an enzyme-selective and time-dependent decline in P450 activities. Whereas the pattern of decline and reversibility of activities were qualitatively similar for CYP3A2, 2C11, 2E1, and 1A1/2, they differed for 2B1/2 and 2D1 in that the decline in the activity was delayed (1 h) for 2B1/2 and not observed for 2D1. This may be attributed to the accessibility of heme or cysteine thiolate and/or the presence/reactivity of critical cysteinyl amino acid residues in various P450 enzymes. Additionally, for most enzymes, the activity showed a biphasic decline, one within 1 h of SNP perfusion and another after 2 h of washout. This was associated with an identical biphasic decline in the microsomal free thiols, presumably due to the rapid and slow reaction of NO and peroxynitrite, respectively, with critical P450 thiols. The short-term effects of NO on P450 are time-dependent and enzyme-selective, with both reversible and irreversible mechanisms.
【翻译】：一氧化氮NO被认为是在感染和炎症中介导CYP450催化活性下降的中间体。此文中，我们在离体灌注的大鼠肝脏模型上观察了NO对P450在时间和可逆性两方面的影响。肝脏用一氧化氮给予体-硝普钠（SNP）恒速灌注0.5或1小时，然后冲洗0-2.5小时。灌注结束后，制备微粒体并进行P450活性以及其他代谢指标的分析。虽然0.5小时NO暴露能使约30%CYP（相对于总含量）不可逆下降，但是一小时NO的暴露能使70%CYP（相对于总含量）不可逆下降。微粒体亚铁血红素的含量的改变与之相一致的。NO的暴露也能使CYP酶活性的选择性和时间依赖性降低。这种下降的方式和活性的不可逆性与CYP3A2, 2C11, 2E1, 1A1/2的含量是一致的，但是2B1/2 和 2D1却不同，因为前者(2B1/2)活性的下降是较滞后的（1h）而后者(2D1)活性却没有改变。这种现象的产生可能是由于各种CYP酶中心血红素的可接近性或者是半胱氨酸巯基的暴露及半胱酰氨主要残基的可反应性相关。此外，对于大部分的酶都具有二次活性降低，首次降低在SNP灌注的1小时内，再次降低是冲洗2小时后。这与线粒体的自由巯基的减少是一致的，其也存在二次减少，进而推测可能分别由于NO的快速反应及过(氧化)亚硝酸盐的迟发反应造成的。短期NO对CYP的影响是时间依赖性和酶选择性的，二者具有可逆和不可逆的机制。
【评论】：首次阐述了NO短期对于CYP的影响。离体大鼠肝脏灌流模型时研究短期NO对CYP影响的理想模型。同时可以进一步考虑给予NO选择性抑制剂（抑制CYP酶活性的降低）或制作病理模型在此基础上观测NO对CYP的影响。
附全文
Vuppugalla R, Mehvar R.
Short-term inhibitory effects of nitric oxide on cytochrome P450-mediated drug metabolism: time dependency and reversibility profiles in isolated perfused rat livers.
Drug Metab Dispos. 2004 Dec;32(12):1446-54. Epub 2004 Dec.
PMID: 15383494
PART 1
2.part1.rar(195.31k)PART 2
2.part2.rar(125.9k)