评估大鼠肝切片作为研究酚类外源性物质同时硫酸化和葡萄糖醛酸化的合适模型系统。

Assessment of rat liver slices as a suitable model system for studying the simultaneous sulphation and glucuronidation of phenolic xenobiotics.

Oddy E A, Manchee G R, Coughtrie M W

Department of Molecular & Cellular Pathology, University of Dundee, Ninewells Hospital and Medical School, UK.

Xenobiotica. 1997 Apr;27(4):369-77. doi: 10.1080/004982597240523.

Abstract

In most mammals, the xenobiotic 1-naphthol undergoes conjugation to produce predominantly the sulphate and glucuronide metabolites. 2. Using 1-naphthol, we established and validated rat liver slices as a model system to assess simultaneously the relative contributions of sulphation and glucuronidation to the metabolism of simple phenolic xenobiotics. 3. Determination of kinetic parameters for 1-naphthol sulphation showed identical affinity (Km approximately 5 microM) in rat liver slices and in rat liver cytosol. 4. In liver slices, at low substrate concentrations (10 microM 1-naphthol), sulphation was the predominant pathway but was readily saturated, whereas at high concentrations of 1-naphthol (100 microM) glucuronidation predominated. 5. In subcellular fractions, the Km for sulphation of 1-naphthol (5 microM) by liver cytosol was substantially lower than the Km for glucuronidation of 1-naphthol (48 microM) in liver microsomes, indicating saturation of sulphation by acceptor substrate was principally responsible for the shift towards glucuronidation at higher concentrations of 1-naphthol.

摘要

在大多数哺乳动物中，外源性物质1-萘酚会进行结合反应，主要生成硫酸盐和葡萄糖醛酸代谢物。2. 我们使用1-萘酚建立并验证了大鼠肝切片作为一种模型系统，用于同时评估硫酸化和葡萄糖醛酸化对简单酚类外源性物质代谢的相对贡献。3. 对1-萘酚硫酸化动力学参数的测定表明，大鼠肝切片和大鼠肝细胞溶胶中的亲和力相同（Km约为5微摩尔）。4. 在肝切片中，在低底物浓度（10微摩尔1-萘酚）下，硫酸化是主要途径，但很容易饱和，而在高浓度的1-萘酚（100微摩尔）下，葡萄糖醛酸化占主导。5. 在亚细胞组分中，肝细胞溶胶对1-萘酚硫酸化的Km（5微摩尔）显著低于肝微粒体中1-萘酚葡萄糖醛酸化的Km（48微摩尔），这表明在较高浓度的1-萘酚下，受体底物对硫酸化的饱和主要导致了向葡萄糖醛酸化的转变。