Murray M, Zaluzny L, Farrell G C
Biochem Pharmacol. 1986 Jun 1;35(11):1817-24. doi: 10.1016/0006-2952(86)90298-4.
The effect of a choline-deficient diet on microsomal cytochrome P-450 and mixed-function oxidase (MFO) activity was investigated in relation to the development of nutritional cirrhosis. In rats that received the choline-deficient diet for 28 weeks cirrhosis was evident macroscopically and histologically; control rats that received an identical diet supplemented with choline had normal livers. Microsomal cytochrome P-450 and cytochrome b5 were reduced in cirrhotic liver to 50% of control levels. Three MFO activities (ethylmorphine N-demethylase, aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-deethylase) were also reduced to 40-70% of control levels. However, the turnover number for the O-deethylation of 7-ethoxycoumarin was not reduced in cirrhotic liver. This finding suggested that certain drug oxidations may be selectively depressed in nutritional cirrhosis. To examine the possibility that selective changes in MFO activity may reflect the suppression of certain cytochrome P-450 isozymes, partially purified fractions of the cytochrome were prepared after solubilisation and hydrophobic affinity chromatography (on n-octylamino-Sepharose 4B) of cirrhotic and control liver microsomes. Analysis of these fractions by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and laser densitometry indicated that a protein band of apparent minimum molecular weight 50.5 kD was primarily affected in cirrhotic rat liver microsomes. Levels of two other bands (apparent minimum molecular weight 48 and 52.5 kD) appeared essentially unaltered. Additional electrophoretic studies, conducted under non-reduced conditions, indicated the haemoprotein nature of protein bands in the 48-55 kD region. These data strongly suggest that cirrhosis produced in rats by a choline-deficient diet is associated with selective decreases in oxidative drug metabolism and individual cytochrome P-450 isozymes.
研究了胆碱缺乏饮食对微粒体细胞色素P-450和混合功能氧化酶（MFO）活性的影响，并探讨其与营养性肝硬化发展的关系。接受胆碱缺乏饮食28周的大鼠，在宏观和组织学上均出现明显的肝硬化；而接受相同饮食但补充了胆碱的对照大鼠肝脏正常。肝硬化肝脏中的微粒体细胞色素P-450和细胞色素b5降至对照水平的50%。三种MFO活性（乙基吗啡N-脱甲基酶、芳烃羟化酶和7-乙氧基香豆素O-脱乙基酶）也降至对照水平的40%-70%。然而，肝硬化肝脏中7-乙氧基香豆素O-脱乙基反应的转换数并未降低。这一发现表明，在营养性肝硬化中某些药物氧化可能被选择性抑制。为了检验MFO活性的选择性变化可能反映某些细胞色素P-450同工酶受抑制的可能性，对肝硬化和对照肝脏微粒体进行溶解和疏水亲和层析（在正辛基氨基琼脂糖4B上）后，制备了细胞色素的部分纯化组分。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和激光密度测定法对这些组分进行分析，结果表明，在肝硬化大鼠肝脏微粒体中，一条表观最小分子量为50.5 kD的蛋白带受到的影响最为显著。另外两条带（表观最小分子量为48和52.5 kD）的水平基本未变。在非还原条件下进行的额外电泳研究表明，48-55 kD区域蛋白带具有血红蛋白性质。这些数据有力地表明，胆碱缺乏饮食诱导大鼠产生的肝硬化与氧化药物代谢和单个细胞色素P-450同工酶的选择性降低有关。
