INTESTINAL SECRETION AND INFLAMMATION--IMPACT OF AMMONIA

肠道分泌和炎症——氨的影响

• 批准号: 2770594
• 负责人: JEFFREY B. MATTHEWS
• 金额: $ 23.3万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-01 至 2000-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2770594
• 关键词: acid base balance; ammonia; chemical structure function; chloride channels; chlorine; colon; cyclic AMP; electrolytes; electrophysiology; gastrointestinal epithelium; gene expression; hydropathy; immunoprecipitation; intestines; ion transport; laboratory rat; membrane transport proteins; potassium; secretion; sodium; tissue /cell culture; transport proteins; voltage /patch clamp

DESCRIPTION: (Adapted from investigator's abstract) Ammonia exerts profound and diverse biological effects on most mammalian cells. The normal colon is exposed to unusually high ammonia concentrations, yet the impact of this simple and ubiquitous substance is largely unknown. The broad intent of this proposal is to explore the interaction of ammonia with the events that comprise regulated intestinal CI- secretion using the T84 human intestinal epithelial cell line and native mammalian tissue as model systems. This proposal builds upon preliminary data that suggest ammonia is a previously unsuspected regulator of colonic electrolyte transport, a finding that may have substantial implications for intestinal function during health and disease. Two groups of studies are planned that will use electrophysiologic methods and isotopic flux analysis, fluorescence-based optical techniques, and cell surface labeling techniques. The first set of studies will expand upon preliminary characterization of the inhibitory effects of ammonia on regulated CI- secretion, comparing results in a cultured cell line to those in a native preparation and specifically examining the apparent selectivity of ammonia for cyclic nucleotide dependent agonists. The basis for the asymmetry in inhibitory potency of ammonia depending upon route of exposure will be explored. The second set of studies will attempt to define the relevant target of ammonia in epithelial cells that accounts for its inhibitory action. These experiments utilize ammonia and related weak bases as physiologic probes into the cellular mechanisms underlying this fundamental and widely distributed epithelial transport process. The hypothesis that ammonia reduces epithelial secretory capacity by perturbing the membrane cycling events that control cell surface expression of specific transport proteins will be addressed. The proposed studies will lay the groundwork for future formalized studies addressing the potential role of ammonia as a pathogenic cofactor in intestinal disease. Because several weak bases appear to share with ammonia the ability to inhibit CI- secretion, these investigations may form the basis for the development of new pharmacologic approaches to the treatment of secretory diarrheal illnesses. By extension, these experiments may yield considerable insight into the biological actions of amines and resolve some of the controversy surrounding their effects on membrane traffic events. These studies may also have broad implications for regulated transport events in organ systems exposed to high levels of ammonia under normal circumstances, during infection with ureolytic organisms, or during hyperammonemic states.

描述：（改编自研究者摘要） 以及对大多数哺乳动物细胞的多种生物学效应。 正常的结肠是 暴露在异常高的氨浓度下，但这种影响 简单而普遍存在物质在很大程度上是未知的。 的广泛意图 这个建议是探索氨与事件的相互作用， 包括使用T84人肠细胞调节肠CI分泌， 上皮细胞系和天然哺乳动物组织作为模型系统。 这 该提案建立在初步数据的基础上，这些数据表明氨是以前 结肠电解质转运的意外调节剂，这一发现可能 对健康期间的肠道功能有实质性的影响， 疾病 计划进行两组研究， 方法和同位素通量分析，荧光光学技术， 和细胞表面标记技术。 第一组研究将扩大 在初步表征氨的抑制作用后， 调节的Cl-分泌，将培养的细胞系中的结果与那些细胞系中的结果进行比较。 在天然制剂中， 环核苷酸依赖性激动剂的氨。 的基础 氨的抑制效力的不对称性取决于暴露途径 将被探索。 第二组研究将试图定义 氨在上皮细胞中的相关目标，占其 抑制作用 这些实验利用氨和相关的弱碱 作为生理学探针， 基本的和广泛分布的上皮转运过程。 的 假设氨通过干扰 控制细胞表面特异性表达的膜循环事件 运输蛋白将被处理。 拟议的研究将为今后的正式研究奠定基础 探讨氨作为致病辅因子在 肠道疾病。 因为几种弱碱似乎与氨共享 抑制Cl-分泌的能力，这些研究可能形成 开发新的药理学治疗方法的基础 分泌性尿道炎的症状 推而广之，这些实验可能会产生 对胺的生物作用有相当深入的了解，并解决了一些问题。 关于它们对膜交通事件的影响的争议。 这些研究也可能对管制运输产生广泛影响 在正常情况下暴露于高水平氨的器官系统中的事件 在某些情况下，在感染溶脲微生物期间，或 高氨血症