ROLE OF ENAC IN NA EXCRETION--INNER MEDULLARY COLLECTING DUCT AND EPITHELIUM

本项目的总体目标是进一步了解 基因产物的调节和功能， 发现了上皮Na通道。 这些研究的背景 与盐敏感性的发病机制有关 高血压 有两个子项目。 第一个子项目 利用新的信息表明， 盐敏感大鼠肾内髓集合管 运输更多的内森做这些细胞培养从 耐盐老鼠 从这些数据得出的假设是， 上皮Na通道复合体异常，或相关的 调节分子，有助于盐的发病机制， 敏感性高血压 实验针对3 具体目标。 第一个目标是确定 已知改变集合管活动的生理操作 钠转运的信使RNA和蛋白质的每3个 主要分单位。 重点将放在肾脏和泌尿上皮上， 但将测量肺和结肠的反应， 检查组织异质性。 第二个目标是确定 上皮Na通道的生物物理特性，因为它存在于 内髓集合管细胞的顶膜， 敏感和耐盐的老鼠。 第三个目标是确定 过表达一种或多种上皮Nachannel的作用 内髓集合管中的亚基对Na转运的影响。 使用转基因小鼠，限速亚基将被选择性地 过度表达，并检查动物的盐敏感性。 这些实验将验证一个假设，即过度活跃的钠 内髓集合管中的通道将有助于 盐敏感性高血压 第二个分项目是根据新的观察结果， 尿上皮含有上皮Nachannel亚单位。 的 本部分提出的实验将检验以下假设： 这些亚单位的功能与它们在 集合管 而不是参与钠重吸收， 假设它们参与机械敏感性的激活， 神经纤维 在肾盂中，传入神经活动明显 由肾盂压力增加激活。 初步数据 表明上皮Nachannel亚单位参与了这一过程， 活动 具体目标是确定机制， 其改善调节传入肾神经的激活 活动 为了确定改善抑制 释放机械感受器激活的假定介质，以及 确定消除一个亚基的影响， 对肾传入神经激活的影响 活动 这些实验将检验一个新的假设， 对钠通道的相互作用有重要意义 功能和中枢神经系统。

The general goal of this project is to further understand the regulation and function of the gene products that form the recently discovered epithelial Na channel. the context in which these studies are undertaken relates to the pathogenesis of salt-sensitive hypertension. There are 2 subprojects. The first subproject capitalizes on new information indicating that primary cultures of the renal inner medullary collecting duct from salt-sensitive rates transport substantially more Nathan do these cells cultured from salt-resistant rats. The hypothesis derived from this data is that an abnormality in the epithelial Na channel complex, or in associated regulatory molecules, contributes to the pathogenesis of salt- sensitive hypertension in humans. the experiments are directed at 3 specific aims. The first aim is to determine the effect of physiologic maneuvers known to alter the activity of collecting duct Na transport on the messenger RNA and protein of each of the 3 major subunits. The focus will be on the kidney and uroepithelium, but responses in lung and colon will be measured in order to examine tissue heterogeneity. The second aim is to determine the biophysical properties of the epithelial Na channel as it exists in the apical membrane of inner medullary collecting duct cells from salt- sensitive and salt-resistant rats. the third aim is to determine the effect of overexpressing one or more of the epithelial Nachannel subunits in the inner medullary collecting duct on Na transport. Using transgenic mice, the rate-limiting subunit will be selectively overexpressed and the animals examined for their salt-sensitivity. These experiments will test the hypothesis that an overactive Na channel in the inner medullary collecting duct will contribute to salt-sensitive hypertension. The second subproject is based on the new observation that the uroepithelium contains epithelial Nachannel subunits. The experiments proposed in this portion will test the hypothesis that these subunits serve a different function that they do in the collecting duct. Rather than participate in Na reabsorption, the hypothesis is that they participate in activation of mechanosensitive nerve fibers. In the renal pelvis, afferent nerve activity is markedly activated by an increase in renal pelvic pressure. Preliminary data suggest that the epithelial Nachannel subunits participate in this activity. the specific aims are to determine the mechanisms by which ameliorate modulates the activation of afferent renal nerve activity. to determine the extent to which ameliorate inhibits the release of putative mediators of mechanoreceptor activation, and to determine the effect of elimination of one of the subunits in genetically altered mice on the activation of afferent renal nerve activity. These experiments will test a novel hypothesis which may have important implications for an interaction of Na channel function and the central nervous system.