MECHANISMS OF CANALICULAR BILE FORMATION

胆管形成机制

• 批准号: 3227809
• 负责人: BRUCE F SCHARSCHMIDT
• 金额: $ 22.52万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1980
• 资助国家: 美国
• 起止时间: 1980-07-01 至 1991-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3227809
• 关键词: acidity /alkalinity; adenosine triphosphate; adenosinetriphosphatase; anions; autoradiography; bile; biological fluid transport; cations; cell membrane; cell morphology; chlorpromazine; corticosteroids; cystic fibrosis; cytoskeleton; electron spin resonance spectroscopy; epithelium; estrogens; ethylene glycols; galactose; gluconeogenesis; glucose; glucose transport; hypertension; inulin; ion transport; liver function; liver metabolism; magnesium; mannitol; membrane activity; membrane lipids; membrane model; membrane permeability; monosaccharides; muscle relaxation; orphan disease /drug; passive transport; phenobarbital; radiotracer; thyroid hormones

This proposal outlines studies to investigate several working hypotheses based upon recent observations from this laboratory and by others which pertain to cellular mechanisms of canalicular bile formation. The proposed studies will (1) examine the possibility that certain bile acids as well as bile acid-independent choleretics stimulate bile flow at the level of the canaliculus by stimulating extrusion of protons across the hepatocyte plasma membrane and raising intracellular pH (pHi) and HCO3- concentratiion, (2) explore the role that Na+/H+ exchange, enhanced ATP-dependent H+ transport mediated by vesicular insertion of H+-ATPase pump units into the plasma membrane, or other possible H+ transport mechanisms play in the postulated dynamic relationship between regulation of pHi and HCO3- secretion, (3) determine whether hepatocytes actively accumulate Cl- via Na+/K+/Cl- cotransport or HCO3-/Cl- exchange and examine the possibility that active Cl- transport plays a role in bile formation, (4) determine whether the Na+-coupled uptake of bile acids is electrogenic or electroneutral, and further explore the mechanisms by which hepatocytes preserve the electrochemical Na+ gradient during the Na+-coupled uptake of bile acids and/or amino acids, (5) quantitatively characterize the relationship between the vesicular blood-to-bile transport of fluid phase markers and overall fluid phase endocytosis by hepatocytes, and (6) explore the level in the endocytic pathway at which ligands destined for bile are segragated from those bound for lysosomes as well as the role of vesicle acidification in this segregation process. These hypotheses will be examined using conventional models and techniques (intact perfused liver, isolated or cultured cells, plasma membrane vesicles) as well as techniques recently acquired or developed by the investigators (conventional and ion-selective microelectrodes, fluorimetric analysis of intact cells and individual vesicles) which have had little prior application to liver and can directly address the novel questions posed. The studies are expected to provide new insight into cellular mechanisms of canalicular bile formation as well as into fundamental, yet poorly understood aspects of epithelial transport in general. The findings will thus be of importance to our current understanding of the pathophysiology of intrahepatic cholestasis as well as of other idseases involving abnormalities in transport, including those affecting the kidney and intestine, cystic fibrosis, and hypertension.

该提议概述了研究几个工作假设的研究 根据该实验室的最新观察以及其他观察结果 与小管胆汁形成有关的细胞机制。 提议 研究将（1）研究某些胆汁酸以及 胆汁酸非依赖性胆固醇刺激胆汁流动 通过刺激质子在肝细胞上的挤出来进行挤出 质膜和升高细胞内pH（PHI）和HCO3- 浓度，（2）探讨Na+/H+交换的作用 ATP依赖性的H+转运由H+ -ATPase的囊泡插入介导 泵单元进入质膜，或其他可能的H+传输 机制在调节之间的假定动态关系中起作用 PHI和HCO3-分泌，（3）确定肝细胞是否主动 通过Na+/K+/Cl- cotransport或HCO3-/Cl-交换累积Cl- 主动Cl-转运在胆汁形成中起作用的可能性， （4）确定胆汁酸的Na+耦合摄取是否为电源 或电荷，并进一步探索肝细胞的机制 在Na+耦合摄取期间保留电化学Na+梯度 胆汁酸和/或氨基酸，（5）定量表征 流体相的囊泡血流转运之间的关系 肝细胞的标记和整体液相内吞作用，（6）探索 配体注定胆汁的内吞途径的水平是 与溶酶体绑定的那些分裂以及囊泡的作用 在此隔离过程中酸化。 这些假设将使用常规模型和技术进行检查 （完整的灌注肝，孤立或培养的细胞，质膜 囊泡）以及最近获得或开发的技术 研究人员（常规和离子选择性微电极，荧光法 完整细胞和单个囊泡的分析）几乎没有 事先应用肝脏，可以直接解决新的问题 摆姿势。 这些研究有望提供有关细胞的新见解 大口管胆汁形成以及基本的机制 一般来说，上皮运输的方面知之甚少。 发现 因此，对于我们当前对 肝内胆汁淤积以及其他IDSESES的病理生理学 涉及运输异常，包括影响肾脏的人 和肠，囊性纤维化和高血压。