Studies on Hepatic Transport and Metabolism of Bilirubin, Bile Acids, and Other Organic Substances.

为了阐明肝细胞对有机离子的转运和代谢及其与临床医学的相关性，进行了以下研究。(1)本文研究了正常和先天性黄疸型高胆红素尿大鼠（EHBR）肝细胞小管膜囊（CMV）对胆汁中有机阴离子普伐他汀的摄取。在ATP和跨膜向上pH梯度的共同存在下，普伐他汀摄取被刺激。这些结果表明，该转运系统可能是有机阴离子通过小管膜的生理性转运系统。(2)结扎胆管（BDL），观察放射性标记的牛磺胆酸盐和普伐他汀的摄取。BDL后2天，这两种转运量均明显减少，这为临床上梗阻性黄疸解除后胆汁流量减少提供了病理生理学依据。(3)吉尔伯特综合征和II型Crigler-Najjar综合征的特征在于肝微粒体胆红素UDP-葡萄糖醛酸基转移酶（BUGT ; UGT 1^** 1）分别降低至正常活性的30%和10%。BUGT基因主要在吉尔伯特综合征中进行分析，大多数病例在编码区发现杂合错义突变或在启动子区发现纯合TATA盒突变（存在额外的TA）。这些结果表明，吉尔伯特综合征是遗传作为一个显性和隐性性状。(4)在转子综合征患者的肝脏中，我们没有发现谷胱甘肽S-转移酶（GST）的免疫组化染色，这表明在肝细胞中没有完整的GST同工酶。(5)结合胆红素等有机阴离子的代谢和转运的文献，对上述结果进行了讨论。

To elucidate hepatocyte transport and metabolism of organic ions and its relevance to clinical medicine, the following studies were perfomed. (1) Uptake of pravastatin, an organic anion excreted into bile, by hepatocyte canalicular membrane vesicles (CMV) from normal and congenitally jaundiced Eisai hyperbilirubinuria rats (EHBR) was studied. Pravastatin uptake was stimulated in the co-presence of ATP and transmembrane upward pH gradient. This transport was absent in EHBR.These results indicate that this transport system may physiologically transport organic anions through canalicular membrane.(2) Bile canalicles were ligated (BDL) and uptakes of radiolabeled taurocholate and pravastatin were observed. Both of the transports decreased markedly 2 days after BDL.This will give pathophysiological basis for reduced bile flow after release of obstrucrive jaundice in clinical medicine. (3) Gilbert's and Type II Crigler-Najjar syndromes are characterized by the decrease in te hepatic microsomal bilirubin UDP-glucuronosyltransferase (BUGT ; UGT 1^<**>1) to 30 and 10 % of the normal activity, respectively. The genes for BUGT was analyzed mainly in Gilbert's syndrome, and heterozygous mis-sense mutations were found in the coding region or homozygous TATA box mutation (presence of additional TA) was found in the promoter region in the most of the cases. These results indicate that Gilbert's syndrome is inherited both as a dominant and a recessive trait.(4) In the liver of patients with Rotor's syndrome, we found no immunohistochemical staining of glutathione S-transferase (GST), indicating the absence of whole GST isozymes in the hepatocytes. (5) The above results were discussed refering to the litratures on the metabolism and transport of bilirubin and other organic anions.