ACTIVE POTASSIUM TRANSPORT ACROSS COLONIC EPITHELIUM

描述：本提案的总体目标是确定 控制活性钾分泌和吸收的调节机制 在哺乳动物的结肠中。 工作模型是空泡柱状细胞 哺乳动物结肠隐窝细胞具有K、Cl和H排出途径 穿过顶膜以及基底外侧的K和Cl通道 膜的 要检验的假设是，协调，虽然 不同激素/调节剂对这些过程的差异调节 负责结肠分泌行为的范围， 上皮 因此肾上腺素和醛固酮引起低流速的液体 分泌被认为是一种调节类型的调节，而 前列腺素E2（PGE 2）引起高流速的液体流动， 更多的是一种冲洗型分泌物。 这两种功能都出现了障碍 空泡化柱状细胞中的调节级联反应将形成 各种胃肠道疾病，从分泌性腹泻到 炎症性肠病 在前两个具体目标中， 在冲洗和调节过程中作用于K和Cl通道的机制 将主要通过膜片钳检查刺激类型 方法论 这些研究将允许在心尖和 基底外侧膜单独研究。 他们将得到补充 通过使用荧光探针测量细胞内Cl， 形态学（微分干涉显微镜）和 生物物理学（膜电容）研究跟踪液泡释放。 在 第三个具体目标，使用荧光探针， 细胞内Ca和H离子通道的调节将是 研究了 初步数据显示这两个人 PGE 2、醛固酮和肾上腺素的作用途径。 此外 将评估顶膜H/K泵活性以及是否存在 原位杂交法测定H/K ATP酶转录本。

DESCRIPTION: The overall goal of this proposal is to determine the regulatory mechanisms controlling active potassium secretion and absorption in the mammalian colon. The working model is that the vacuolated columnar cells of the mammalian colonic crypt possess pathways for K, Cl and H exit across the apical membrane as well as K and Cl channels on the basolateral membrane. The hypothesis to be tested is that the coordinated, albeit differential regulation, of these processes by different hormones/modulators is responsible for the range of secretory behavior exhibited by the colonic epithelium. Thus epinephrine and aldosterone cause a low rate of fluid secretion that is proposed to be a modulatory type of regulation whereas prostaglandin E2 (PGE2) causes a high rate of fluid flow that is proposed to be more of a flushing type of secretion. A dysfunction in either of these regulatory cascades in the vacuolated columnar cells would form the basis of a variety of gastrointestinal diseases ranging from secretory diarrhea to inflammatory bowel disease. In the first two specific aims the regulatory mechanisms acting on K and Cl channels during the flushing and modulatory type of stimulation will be examined, largely through patch clamp methodology. These studies will allow the events at the apical and basolateral membranes to be studied separately. They will be complemented by measurements of intracellular Cl using a fluorescent probe, and by morphological (differential interference contrast microscopy) and biophysical (membrane capacitance) studies to track vacuole release. In the third specific aim, using fluorescent probes, the involvement of intracellular Ca and H in the regulation of the ion channels will be investigated. Preliminary data suggest the involvement of these two pathways in the actions of PGE2, aldosterone and epinephrine. In addition apical membrane H/K pump activity will be assessed and the presence of an H/K ATPase transcript determined by in situ hybridization.