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 新近形成的基因产物的调节和功能 发现了上皮性钠通道。这些研究的背景 都与盐敏感的发病机制有关 高血压。共有2个子项目。第一个子项目 利用新的信息表明， 盐敏感大鼠肾髓内集合管的实验研究 运输比这些细胞培养出来的细胞要多得多 耐盐的老鼠。从这些数据中得出的假设是 上皮性钠通道复合体异常，或相关的 调节分子，在盐的发病机制中起作用- 人类的敏感型高血压。实验是在3点进行的。 明确的目标。第一个目标是确定 已知的生理动作可以改变集合管的活性 3种病毒的信使RNA和蛋白质上的NA转运 主要亚基。重点将放在肾脏和尿路上皮上， 但将测量肺和结肠的反应，以便 检查组织的异质性。第二个目标是确定 上皮性钠离子通道的生物物理特性 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的效果 内髓集合管中的亚单位对钠转运的影响。 利用转基因小鼠，限速亚单位将被选择性地 过度表达，并检查这些动物对盐的敏感性。 这些实验将检验一种假设，即一种过度活跃的钠 内髓集合管中的通道将有助于 盐敏性高血压。 第二个分项目基于新的观察结果，即 尿路上皮含有上皮性Nachannel亚单位。这个 这一部分提出的实验将检验这样的假设 这些亚基的功能与它们在 收集风管。不是参与钠的重吸收，而是 假说是它们参与了机械敏感性的激活 神经纤维。在肾盆，传入神经活动明显。 肾盆腔压力增加而激活。初步数据 提示上皮性Nachannel亚单位参与这一过程 活动。具体目标是通过以下方式确定机制 改善肾传入神经的激活 活动。以确定改善在多大程度上抑制 机械感受器激活的可能介体的释放，以及 确定消除其中一个亚基的效果 转基因小鼠对肾传入神经的激活作用 活动。这些实验将检验一种新的假设，它可能 对钠离子通道的相互作用有重要的意义 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.