Ekins S, Williams J A, Murray G I, Burke M D, Marchant N C, Engeset J, Hawksworth G M
Department of Medicine and Therapeutics, University of Aberdeen.
Drug Metab Dispos. 1996 Sep;24(9):990-5.
Human, rat, and dog phase I and phase II xenobiotic metabolism in precision-cut liver slices and freshly isolated hepatocytes was compared using a range of substrates. Carbamazepine (50 microM) and styrene (2 mM) were used as probes to study the maintenance of cytochrome P450 and epoxide hydrolase-mediated metabolism in male Sprague-Dawley rat, precision-cut liver slices and hepatocytes. Carbamazepine metabolism in both models resulted in the formation of the bioactive 10,11-epoxide (KM = 766 microM and Vmax = 2.5 pmol/min/mg protein in precision-cut slices). Epoxide formation was higher (2.4-fold) in hepatocytes than slices. Styrene was deactivated to styrene diol at a higher rate in hepatocytes (9.7-fold) than slices. The lower rate of metabolism in slices compared with hepatocytes confirms our previous observations using testosterone, 7-ethoxycoumarin, 1-chloro-2,4-dinitrobenzene and 2-(5'-chloro-2'-phosphoryloxyphenyl)-6-chloro-4-(3H)-quinazolinone in the rat. Testosterone 6 beta-hydroxylation in human liver slices was similar to cultured hepatocytes, but lower than in freshly isolated hepatocytes. 7-Ethoxycoumarin O-deethylation was higher in freshly isolated human hepatocytes, as was the ratio of glucuronide to 7-hydroxycoumarin. Testosterone hydroxylations, 7-ethoxycoumarin O-deethylation, and 1-chloro-2,4-dinitrobenzene conjugation were also lower in male beagle dog slices, compared with freshly isolated hepatocytes. Attempts at long-term preservation of dog liver slices using vitrification and storage for up to 9 days at -196 degrees C resulted in the retention of phase I and phase II metabolism, although conjugation was lower than in freshly prepared slices. Xenobiotic metabolism in short-term incubations is consistently lower in dog and rat precision-cut slices than in freshly isolated hepatocytes; whereas, in humans, this quantitative difference is partly hidden by the large interindividual variation.
使用一系列底物比较了人、大鼠和犬在精密肝切片和新鲜分离的肝细胞中的I期和II期异源物代谢。卡马西平（50微摩尔）和苯乙烯（2毫摩尔）用作探针，以研究雄性Sprague-Dawley大鼠、精密肝切片和肝细胞中细胞色素P450和环氧水解酶介导的代谢的维持情况。两种模型中的卡马西平代谢均导致生物活性10,11-环氧化物的形成（在精密切片中，米氏常数 = 766微摩尔，最大反应速度 = 2.5皮摩尔/分钟/毫克蛋白质）。肝细胞中环氧化物的形成比切片中的更高（2.4倍）。与切片相比，肝细胞中苯乙烯失活形成苯乙烯二醇的速率更高（9.7倍）。与肝细胞相比，切片中代谢速率较低，这证实了我们之前在大鼠中使用睾酮、7-乙氧基香豆素、1-氯-2,4-二硝基苯和2-(5'-氯-2'-磷酸氧苯基)-6-氯-4-(3H)-喹唑啉酮的观察结果。人肝切片中睾酮6β-羟基化与培养的肝细胞相似，但低于新鲜分离的肝细胞。新鲜分离的人肝细胞中7-乙氧基香豆素O-脱乙基化更高，葡萄糖醛酸苷与7-羟基香豆素的比率也是如此。与新鲜分离的肝细胞相比，雄性比格犬切片中睾酮羟基化、7-乙氧基香豆素O-脱乙基化和1-氯-2,4-二硝基苯结合也较低。使用玻璃化法对犬肝切片进行长期保存，并在-196℃下储存长达9天，尽管结合作用低于新鲜制备的切片，但I期和II期代谢得以保留。在短期孵育中，犬和大鼠精密肝切片中的异源物代谢始终低于新鲜分离的肝细胞；而在人类中，这种数量差异部分被个体间的巨大差异所掩盖。
