Shull L R, Kirsch D G, Lohse C L, Wisniewski J A
Xenobiotica. 1987 Mar;17(3):345-63. doi: 10.3109/00498258709043944.
A definitive hazard assessment of xenobiotics translocated through food animals into edible products such as meat or milk requires a complete analysis of metabolism in food animals. However, large animal metabolism studies present many experimental difficulties. None of several in vitro alternatives such as subcellular fractions has been established as an acceptable predictor of in vivo metabolism. The feasibility of using isolated hepatocytes to predict the metabolism of xenobiotics, both quantitatively and qualitatively, in large ruminant animals (e.g. cattle) is being studied in our laboratory. A procedure was developed for isolating hepatocytes aseptically from the caudate process of the liver which was obtained surgically from 100-125 kg calves. A modified two-step vascular perfusion procedure provides hepatocyte suspensions that are typically greater than or equal to 85% viable and greater than or equal to 1 X 10(7) viable hepatocytes/g of liver (wet wt). Xenobiotic metabolism has been evaluated in suspensions and primary cultures using aldrin epoxidation, ethoxycoumarin O-deethylation, and 7-hydroxycoumarin glucuronidation and sulfation. Metabolic activities are relatively short-lived in suspensions less than or equal to 4 h, but quite stable up to 10 h when cultured on collagen-coated plates in chemically defined medium. Bovine hepatocytes behave similarly in culture to rodent hepatocytes. Although primary culturing of hepatocytes is more difficult than suspensions, primarily due to the asepsis requirements, it is the method of choice for xenobiotic metabolism determinations in isolated hepatocytes of cattle.
要对通过食用动物转移到肉类或牛奶等可食用产品中的外源化合物进行确定性危害评估，需要对食用动物的代谢进行全面分析。然而，大型动物代谢研究存在许多实验困难。几种体外替代方法，如亚细胞组分，均未被确立为体内代谢的可接受预测指标。我们实验室正在研究使用分离的肝细胞来定量和定性预测大型反刍动物（如牛）中外源化合物代谢的可行性。已开发出一种从100 - 125千克小牛手术获取的肝脏尾状叶无菌分离肝细胞的方法。一种改良的两步血管灌注程序可提供通常存活率大于或等于85%且每克肝脏（湿重）活肝细胞数大于或等于1×10⁷的肝细胞悬液。已使用艾氏剂环氧化、乙氧基香豆素O - 去乙基化以及7 - 羟基香豆素葡萄糖醛酸化和硫酸化在悬液和原代培养物中评估了外源化合物代谢。在小于或等于4小时的悬液中，代谢活性持续时间相对较短，但在化学限定培养基中于胶原包被板上培养长达10小时时相当稳定。牛肝细胞在培养中的行为与啮齿动物肝细胞相似。虽然肝细胞原代培养比悬液培养更困难，主要是由于无菌要求，但它是测定牛分离肝细胞中外源化合物代谢的首选方法。
