HEPATIC FORMATION AND HANDLING OF DRUG METABOLITES

研究计划的长期目标是提供全面的 了解与药物相关的空间和时间相关变化 主要药物在肝脏中消失和代谢形成 代谢器官。 探测区域代谢异质性的方法： 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，肝 动脉-肝静脉 [HAPV-HAHV，具有给定底物的双流入系统 HA]灌注和多指示剂稀释（MID）技术将 用于检查消除和转运机制 几个前体代谢物对的肝细胞膜。一针注射 血管混合物[51Cr标记的红细胞，125I标记的 白蛋白、58CoEDTA（类似于[14C]蔗糖）]和细胞 (D2O) 参考 非消除指示剂以及 14C 和 3H 标记的前体和产物 将在通过 PR 或 HAPV-HAHV 进行稳态大量灌注期间给予。的 由此获得的流出曲线将被适当分析和 参考非消除参考指标。 建模能够解释红细胞的结合效应， 血浆或组织蛋白提供生理体积和 前体和前体的流入、流出和封存系数 代谢，并确定速率控制步骤。对于目标 1，肝脏 苯甲酸、马尿酸、牛磺石胆酸3-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、 哈啰酚、硫酸哈啰酚和葡萄糖醛酸结合物、硫酸雌酮、 雌酮和雌二醇（含或不含抑制剂 硫酸化/脱硫）将被检查。胆汁的硫酸盐结合物 同时给予雌酮、4-MU 或哈罗酚进行测试 用于运输和移除中的相互作用。对于目标 2，微混合 肝动脉和门静脉将通过全套检查进行检查 使用 HA 或 PV 注射，然后使用 HA 或 PV 的非消除参考 输注载体介导的[溴磺酞（BSP）及其 谷胱甘肽结合物 (BSP-GSH)] 和限流（水杨酰胺） 不同 HA:PV 流量比的基材。 事件基础单一， 平行和顺序途径、无效循环、酶分区和 上述研究将提供吸收竞争。 的 胆管周围毛细血管丛对溶质的渗透性和 将探针注入 HA 可能会减少肝脏质量 被划定。这些研究应该为机制提供重要的见解 药理上重要的硫酸盐的药物代谢加工和 葡萄糖醛酸结合物，以及预形成与生成的差异 由于来源不同而去除代谢物。

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.