MECHANISMS OF BILE PIGMENT EXCRETION

利用细胞生物学、生物化学、生物物理学和免疫形态学 方法，我们寻求继续研究参与的机制， 胆红素和其他有机阴离子从血液转移到胆汁。 (1)的 肝内皮细胞窗孔在控制肝细胞摄取中的作用 胆红素和其他物质将根据表征进行研究 和对吸收机制的影响， 离体灌流大鼠肝脏。 (2)来自不同亚型的独特肽 正常和突变（古恩）大鼠的UDP葡萄糖醛酸基转移酶将 测序并用于合成寡核苷酸探针以鉴定 异构体特异性cDNA;长期目标是纠正缺陷 古恩大鼠和Crigler-Najjar患者的胆红素UDPGI活性 综合征，I型。 (3)胆汁淤积的细胞机制研究 将使用分离的肝细胞和来自 肝细胞质膜的窦状结构域和小管结构域; 特别是，膜脂的作用，流动性，极性和 正弦域中的传输事件与观测到的传输事件之间的关系 小管结构和功能缺陷。 一个新的假设， 一组小管质膜外“ATP酶”保护肝细胞 细胞外ATP浓度也将被测试。 (4)功能 将使用窦和小管进行结构研究 来自常染色体Recombinant遗传动物的质膜囊泡 影响胆红素和其他有机物的膜转运缺陷 阴离子。 该组包括杂合子和纯合子的“摄取 Southdown羊中的“缺陷”，Corriedale羊中的Dubin-Johnson综合征， 和新描述的Wistar大鼠结合性高胆红素血症， 纯合子无胸腺：杂合子古恩大鼠杂种中的胆汁淤积 炔雌醇给药。 目标是定义基本的交通工具 这些突变体的缺陷。

Using cell biological, biochemical, biophysical and immunomorphological methods, we seek to continue studies of the mechanisms involved in the transfer of bilirubin and other organic anions from blood to bile. (1) The role of hepatic endothelial cell fenestrae in controlling the uptake of bilirubin and other substances will be studied based upon characterization of fenestral dynamics in culture and effects on uptake mechanisms in isolated perfused rat liver. (2) Unique peptides from different isoforms of UDP glucuronyl transferase from normal and mutant (Gunn) rats will be sequenced and used for synthesis of oligonucleotide probes to identify isoform-specific cDNAs; the long range goal is to correct defective bilirubin UDPGI activity in Gunn rats and patients with the Crigler-Najjar syndrome, Type I. (3) Study of cellular mechanisms involved in cholestasis will be performed using isolated hepatocytes and vesicles derived from the sinusoidal and canalicular domains of the plasma membrane of hepatocytes; specifically, the role of membrane lipids, fluidity, polarity and the relation between transport events in the sinusoidal domain and observed defects in canalicular structure and function. A novel hypothesis that a group of canalicular plasma membrane ecto-"ATPases" protect hepatocytes from extracellular ATP concentrations will also be tested. (4) Functional and structural studies will be performed using sinusoidal and canalicular plasma membrane vesicles from animals with autosomal recessively inherited defects in membrane transport affecting bilirubin and other organic anions. The group includes heterozygotes and homozygotes for an "uptake defect" in Southdown sheep, the Dubin-Johnson syndrome in Corriedale sheep, and newly described conjugated hyperbilirubinemia in Wistar rats and cholestasis in homozygous athymic:heterozygous Gunn rat hybrids after administration of ethinyl estradiol. The goal is to define basic transport defects in these mutants.