HEPATIC FORMATION AND HANDLING OF DRUG METABOLITES

这项研究提案的长期目标是提供一个彻底的 理解与药物相关的时空变化 主要药物在肝脏中的消失和代谢物形成 新陈代谢器官。探测地带性代谢异质性的方法： 单程顺行[P，流入门静脉(PV)]和逆行[R， 流入肝静脉[HV]和肝动脉-门静脉 动脉-肝静脉[HAPV-HAHV，带底物的双流入系统 到HA]灌注和多指示剂稀释(MID)技术 被用来检查消除和转移的机制 几种前体-代谢物对的肝细胞膜。一针 血管的混合物[~(51)Cr标记的红细胞，~(125)I标记的红细胞 白蛋白，58CoEDTA(类似于[14C]蔗糖)]和细胞(D2O)参考 未消除的指示剂和~(14)C和~3H标记的前体和产物 将在稳定状态下由PR或HAPV-HAHV进行批量灌流。这个 将对由此获得的流出剖面进行适当的分析和 相对于未消除的参考指标进行参考。 建模能够解释由于红细胞的结合效应， 血浆，或组织蛋白，提供生理容量和 前驱和前驱体的流入、流出和封存系数 代谢物，并确定速率控制步骤。对于目标1，肝脏 3-苯甲酸、马尿酸、牛磺胆酸的加工 硫酸盐、示踪剂水杨酰胺和非那西丁、吗啡、吗啡-3β-和 6β-葡萄糖醛酸苷、4-甲基伞形酮(4MU)、4MU葡萄糖醛酸苷、 哈莫尔，哈莫尔硫酸盐和葡萄糖醛酸偶联物，硫酸雌酮， 雌酮和雌二醇(带和不带抑制剂) 硫化/脱硫法)将被审查。胆汁的硫酸盐结合物 酸，雌酮，4-MU或Harmol同时给药进行试验 用于运输和搬运过程中的相互作用。对于目标2，微观混合 将对肝动脉和门静脉进行全套检查 未消除的引用使用HA或PV注射，然后使用HA或PV 载体介导的[溴代磺化邻苯二甲酸二异丙酯(BSP)]及其 谷胱甘肽结合物(BSP-GSH)]和限流性(水杨酰胺) 在不同的HA：PV流量比下的衬底。单曲背后的事件， 平行和连续的途径，无效的循环，酶的区带，以及 上述研究将提供吸收方面的竞争。这个 胆管周围毛细血管丛对溶质的通透性 通过将探针注入HA，可能会减少肝脏质量 被描绘出来。这些研究应该对机制有重要的洞察力 重要的药用硫酸盐的药物代谢物加工和 葡萄糖醛酸偶联物，以及预制和生成的差异 由于来源不同而导致的代谢物清除。

The long-term goal of the research proposal is to provide a thorough understanding of the space- and time-related changes associated with drug disappearance and metabolite formation in the liver, the major drug metabolizing organ. Methods for probing zonal metabolic heterogeneities: single pass prograde [P, inflow into portal vein (PV)] and retrograde [R, inflow into hepatic vein (HV)] and hepatic artery-portal vein, hepatic artery-hepatic vein [HAPV-HAHV, dual inflow system with substrates given to HA] perfusion and the multiple indicator dilution (MID) technique will be used to examine mechanisms of elimination and transport across hepatocyte membranes for several precursor-metabolite pairs. An injection of a mixture of vascular [51Cr-labeled red blood cells, 125I-labeled albumin, 58CoEDTA (similar to [14C]sucrose)] and cellular (D2O) reference noneliminated indicators and 14C- and 3H-labeled precursor and product will be given, during steady-state bulk perfusion by PR or HAPV-HAHV. The outflow profiles thus obtained will be appropriately analyzed and referenced with respect to the noneliminated reference indicators. Modeling is able to account for the binding effects due to red cells, plasma, or tissue proteins, provide the physiological volumes and the influx, efflux, and sequestration coefficients for both precursor and metabolite, and identify the rate-controlling step. For Aim 1, the hepatic processing of benzoic acid, hippuric acid, taurolithocholic acid 3- sulfate, tracer salicylamide and phenacetin, morphine, morphine-3beta- and 6beta- glucuronides, 4-methyl-umbelliferone (4MU), 4MU glucuronide, harmol, harmol sulfate and glucuronide conjugates, estrone sulfate, estrone, and estradiol (with and without inhibitors of sulfation/desulfation) will be examined. The sulfate conjugate of the bile acid, and of estrone, 4-MU or harmol will be given simultaneously to test for interactions in transport and removal. For Aim 2, the micro-mixing of the hepatic artery and portal vein will be investigated with a full set of noneliminated references with HA or PV injections, then with HA or PV infusion of carrier-mediated [bromosulfophthalein (BSP) and its glutathione conjugate (BSP-GSH)] and flow-limited (salicylamide) substrates at varying HA:PV flow ratios. Events underlying single, parallel, and sequential pathways, futile cycling, enzyme zonation, and competition in uptake will be provided in the above studies. The permeability of the peribiliary capillary plexus to solutes and the potential reduction in liver mass with the probes infused into the HA will be delineated. These studies should lend important insight into mechanisms of drug-metabolite processing of pharmacologically important sulfate and glucuronide conjugates, and differences in preformed vs. generated metabolite removal due to the differing origins.