Regulation of Secretory Ion Channels in Colonic Crypts

结肠隐窝分泌离子通道的调节

• 批准号: 7216200
• 负责人: DAN R HALM
• 金额: $ 25.85万
• 依托单位: WRIGHT STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-05-15 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7216200
• 关键词: Adverse effects; Apical; Back; Binding; Categories; Cells; Clinical; Columnar Cell; Condition; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cystic Fibrosis; Defensins; Dehydration; Diarrhea; Epithelial Cells; Epithelium; Equilibrium; Event; Excision; Fluids and Secretions; Fluorescent Probes; Flushing; Functional disorder; Gastrointestinal Diseases; Indium; Inflammatory Bowel Diseases; Inflammatory Response; Intervention; Intestines; Ion Channel; Ion Transport; Ions; Lead; Life; Liquid substance; Membrane; Modeling; Molecular; Monitor; Mucous body substance; Nature; Output; Pathway interactions; Patients; Pharmacologic Substance; Physiological; Potassium Channel; Process; Production; Prostaglandins; Protein Kinase C; Rate; Regulation; Research Personnel; Role; Route; Second Messenger Systems; Secretory Rate; Signal Pathway; Signal Transduction; Site; Source; Stimulus; Techniques; Testing; Therapeutic Intervention; Thinking; Ulcerative Colitis; Water; Work; apical membrane; base; basolateral membrane; colonic crypt; driving force; insight; interstitial; patch clamp; programs; receptor; response; second messenger; therapy design

DESCRIPTION (provided by applicant): The central objective of this project is to determine the mechanisms regulating Cl- and K+ channels involved in active Cl- and K+ secretion across the mammalian colonic epithelium, since these channels are key elements in stimulating these distinct modes of ion secretion; Mucosal secretory responses are a balance between activator and repressor pathways. Secretory diarrhea can result from a pathophysiologic stimulation of crypt epithelial cells, which actively secrete Cl- and K+ in response to increased intracellular cAMP. Conditions such as inflammatory bowel disease and cystic fibrosis also lead to altered ion and water transport via actions at these secretory epithelial cells. Inappropriate inhibitions of repressor pathways, in particular, are a likely source of secretory diarrhea for patients with ulcerative colitis. The working model is that active secretory processes for Cl- and K+ occur in columnar cells of the colonic crypt epithelium, such that these cells are a locus of dysfunction in many gastrointestinal diseases. Ion channels involved in Cl- and K+ secretion will be examined using patch-clamp electrophysiologic techniques to record membrane ionic currents. Recordings from isolated crypts allow study of both apical and basolateral membrane channels as well as the second messengers controlling ion channel activity. Fluorescent probes will be used to monitor involvement of cell Ca++ and pH as second messengers controlling ion channels. The specific aims are to determine regulatory mechanisms for the basolateral membrane K+ channels, the Cl- basolateral membrane channels and the apical membrane K+ and Cl- channels involved in fluid secretion. The long-term objective is to determine the regulatory mechanisms acting on the multiple secretory functions of intestinal epithelial cells during physiologic stimulation. These distinct modes of ion channel control are the basis for excessive and impaired secretory functions that occur in secretory diarrhea, ulcerative colitis and cystic fibrosis. The close relationship between prostaglandin stimulation of secretion and inflammatory responses provides an opportunity to develop pharmaceutical agents that differentially target the prostanoid receptor subtypes involved. Differences in the ion channel types supporting each mode of secretion also can be exploited to develop further agents for selective clinical intervention, without producing deleterious side effects. Thus, this project will lead to greater insight into the regulatory control of colonic fluid secretion and likely to therapeutic interventions for patients with life-threatening secretory activity.

描述（由申请人提供）：本项目的主要目的是确定调节哺乳动物结肠上皮中活性Cl-和K+分泌所涉及的Cl-和K+通道的机制，因为这些通道是刺激这些不同离子分泌模式的关键要素;粘液分泌反应是激活剂和阻遏剂途径之间的平衡。分泌性腹泻可由隐窝上皮细胞的病理生理刺激引起，隐窝上皮细胞响应于细胞内cAMP增加而主动分泌Cl-和K+。炎症性肠病和囊性纤维化等疾病也会通过这些分泌性上皮细胞的作用导致离子和水转运的改变。特别是阻遏物通路的不适当抑制可能是溃疡性结肠炎患者分泌性腹泻的一个来源。工作模型是，积极的分泌过程中发生的Cl-和K+的柱状细胞的结肠隐窝上皮，这些细胞是一个位点的功能障碍，在许多胃肠道疾病。将使用膜片钳电生理技术检查涉及Cl-和K+分泌的离子通道，以记录膜离子电流。记录从孤立的隐窝允许研究顶端和基底侧膜通道以及第二信使控制离子通道的活动。荧光探针将用于监测细胞Ca++和pH作为控制离子通道的第二信使的参与。具体的目的是确定调节机制的基底外侧膜K+通道，Cl-基底外侧膜通道和顶端膜K+和Cl-通道参与液体分泌。长期目标是确定在生理刺激过程中对肠上皮细胞的多种分泌功能起作用的调节机制。这些不同的离子通道控制模式是分泌性腹泻、溃疡性结肠炎和囊性纤维化中发生的分泌功能过度和受损的基础。前列腺素刺激分泌和炎症反应之间的密切关系提供了一个机会，开发药物的差异靶向前列腺素受体亚型参与。还可以利用支持每种分泌模式的离子通道类型的差异来开发用于选择性临床干预的其他试剂，而不产生有害的副作用。因此，该项目将导致对结肠液分泌的调节控制有更深入的了解，并可能对具有危及生命的分泌活动的患者进行治疗干预。