EFFECTS OF ALCOHOL ON HEPATIC DRUG METABOLISM

最终的目标是描绘长期的机制， （慢性）暴露于酒精饮料改变药物代谢 在肝脏中的功能。 该实验系统由一个主要的 培养鸡胚肝细胞，可测定 酒精和其他药物对肝脏的直接影响。 我们发现，像乙醇这样简单的化学物质， 市售酒精饮料中的链醇导致 细胞色素P450（P450）、UPD葡糖醛酸基转移酶（UDPGT）和 5-氨基乙酰丙酸（ALA）合酶。 的 醇类都诱导了一种分子量为50 K的蛋白质， 用抗纯化的P450同工酶的抗血清， 苯巴比妥类诱导剂。 抗原同源性和底物 诱导的UDPGT和P450的特异性表明，2-至5-碳 醇类在这些肝细胞中引起苯巴比妥样诱导。 本研究拟从鸡中分离纯化乙醇诱导的P450同工酶 胚胎，并与P450同工酶进行比较， 苯巴比妥或甲基胆蒽样诱导剂，如底物 P450同工酶的特异性、肽图、抗原性和分离 采用HPLC 我们已经表明，诱导P450的各种醇和吡唑， 几乎完全取决于这些化合物的疏水性。 我们还将 用不同疏水性或 电子成分，以确定是否与疏水性相关 对于P450的诱导适用于这些苯巴比妥样诱导剂或仅 适用于醇和吡唑。 乙醇代谢的程度存在相当大的争议， 完整肝脏中的P450。 我们已经测量了乙醇代谢， 完整的培养鸡肝细胞，发现乙醇代谢的变化 对应于醇脱氢酶活性的变化。 我们提出 实验以确定细胞色素P450的变化，如诱导， 乙醇或胡椒基丁醚抑制，对乙醇有任何影响 由完整的细胞进行代谢。 如果乙醇对P450的诱导作用增加， 在这些细胞中的乙醇代谢，我们将确定特异性，如果 引起这种增加的各种P450诱导剂。

The ultimate goal is to delineate the mechanisms by which long-term (chronic) exposure to alcoholic beverages alters drug metabolising functions in the liver. The experimental system consists of a primary culture of chicken embryo hepatocytes which allows the determination of direct effects of alcohols and other agents on the liver. We have found that chemicals as simple as ethanol and the major higher chain alcohols in commercial alcoholic beverages cause induction of cytochrome P450 (P450), UPD Glucuronyl Transferase (UDPGT), and 5-aminolevulinate (ALA) synthase in these cultured hepatocytes. The alcohols all induce a protein of 50K molecular weight that cross-reacts with antisera prepared against purified isozymes of P450 induced by phenobarbital-like inducers. The antigenic homology and the substrate specificities of induced UDPGT and P450 suggest that 2- to 5-carbon alcohols are causing a phenobarbital-like induction in these hepatocytes. We propose to purify ethanol-inducible isozyme(s) of P450 from chicken embryos and compare their characteristics with isozymes of P450 induced by phenobarbital or methylcholanthrene-like inducers, such as substrate specificity, peptide maps, antigenicity and separation of the P450 isozymes by HPLC. We have shown that induction of P450 by various alcohols and pyrazoles depends almost entirely on hydrophobicity of these compounds. We will also test phenobarbital-like inducers of P450 with different hydrophobic or electronic constituents to determine if the correlation with hydrophobicity for induction of P450 applies to these phenobarbital-like inducers or only applies to alcohols and pyrazoles. Considerable controversy exists over the extent of ethanol metabolism by P450 in the intact liver. We have measured ethanol metabolism by the intact cultured chick hepatocytes and found changes in ethanol metabolism corresponding to changes in alcohol dehydrogenase activities. We propose experiments to determine if changes in cytochrome P450 such as induction by ethanol or inhibition by piperonyl butoxide, has any effect on ethanol metabolism by the intact cells. If induction of P450 by ethanol increases ethanol metabolism in these cells, we will determine the specificity, if any, of various inducers of P450 to cause this increase.