INTESTINAL SECRETION AND INFLAMMATION--IMPACT OF AMMONIA

描述：(改编自调查人员摘要)氨对人体产生深远影响 以及对大多数哺乳动物细胞的不同生物学效应。正常的冒号是 暴露在异常高的氨浓度下，但这一影响 简单而普遍存在的物质在很大程度上是未知的。的广泛意图 这一提议是为了探索氨与 包括使用T84人体肠道调节的肠道CI分泌 上皮细胞系和天然哺乳动物组织作为模型系统。这 这项提议建立在初步数据的基础上，这些数据表明氨是以前的 结肠电解质转运的意外调节，这一发现可能 对健康和健康期间的肠道功能有重大影响 疾病。计划进行两组研究，这些研究将使用电生理 方法和同位素流量分析，基于荧光的光学技术， 和细胞表面标记技术。第一组研究将扩大 关于氨的抑制作用的初步表征 调节CI分泌，将培养细胞系的结果与 在原生制剂中，并具体检查表观选择性 用于环核苷酸依赖激动剂的氨。的基础是 氨的抑制效力不对称取决于接触途径 将会被探索。第二组研究将试图定义 上皮细胞中氨的相关靶点解释了其 抑制作用。这些实验利用氨和相关的弱碱。 随着生理学对这一现象背后的细胞机制的研究 基本的和广泛分布的上皮运输过程。这个 氨通过扰动降低上皮细胞分泌能力的假说 控制细胞表面特异性表达的膜循环事件 运输蛋白将被提及。 拟议的研究将为未来的正式研究奠定基础。 解决氨作为致病辅助因子的潜在作用 肠道疾病。因为几个弱碱似乎与氨有共同之处 抑制CI分泌的能力，这些研究可能形成 开发新的治疗药物的药理学方法的基础 分泌性腹泻的疾病。推而广之，这些实验可能会产生 对胺的生物学行为有相当深入的了解，并解决了一些 围绕它们对膜交通事件的影响的争议。 这些研究也可能对管制交通产生广泛的影响。 正常情况下暴露于高水平氨的器官系统中的事件 在感染溶脲微生物期间，或在 高氨化状态。

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.