REGULATION OF SODIUM PUMPS IN THE KIDNEY

肾脏盐转运的调节对于维持细胞外 容量和血压。 本提案的目的是确定 两个关键的稳态利钠尿的分子机制 在近端小管（PT）中发生的反应。 1)急性升高 在动脉压迅速降低PT盐和容量重吸收， 从而增加对致密斑的递送，这是 自动调节，并有助于压力尿钠排泄。 这 一个实验室已经证明了钠泵从表面的重新分布 在这个反应中假定的内部存储。 2)高盐饮食 引起慢性减少的分数重吸收的盐在 PT. 这个实验室已经证明，Na，K-ATP酶β，而不是 在该模型中α表达降低。 这两种利尿钠 高血压的反应会改变。 我们将应用亚细胞 分级分离方法，以鉴定表面和细胞内膜， 这些细胞中转运蛋白丰度和活性模式的变化 对利钠刺激的反应。 三个假设将是 测试与目标有关。 1)检验假设， 在两种表面和细胞膜中的Na，K-ATP酶α β异二聚体和NHE池， 肾细胞中的细胞内膜，以及α和 β亚基不组装为α β异二聚体; 确定这些细胞内池是否可以被募集到细胞内。 质膜，并测试再分配的假定介质。 （二） 检验PT钠转运的快速减少， 伴随着动脉压的急性增加是由于减少 钠泵和NHE交换剂的表面表达和/或活性。 确定响应的时间过程和可逆性，测试 反应的假定介质，以及反应是否改变 在高血压模型中。 3)检验假设， Na，K-ATP酶亚基之一的产生限制了 在PT质膜中表达的活性钠泵，可以限制 钠转运 确定对照组对高盐饮食的反应 和高血压大鼠，以及是否反义α或β也限制了 钠泵的生产。 实现我们的目标将 有助于我们理解这些利钠素的改变 反应可能是机械地参与生成或 维持高血压。

Regulation of renal salt transport is essential to maintain extracellular volume and blood pressure. The objective of this proposal is to define the molecular mechanisms responsible for two key homeostatic natriuretic responses that occur in the proximal tubule (PT). 1) An acute increase in arterial pressure rapidly decreases PT salt and volume reabsorption, thereby increasing delivery to the macula densa, a key signal for autoregulation, and contributing to pressure natriuresis. This laboratory has demonstrated a redistribution of sodium pumps from surface to putative internal stores in this response. 2) A high salt diet provokes a chronic decrease in the fractional reabsorption of salt in the PT. This laboratory has demonstrated that Na,K-ATPase beta, but not alpha expression is decreased in this model. Both of these natriuretic responses are altered in hypertension. We will apply subcellular fractionation methods to identify surface and intracellular membranes and the change in the patterns of transporter abundance and activity in these pools in response to the natriuretic stimuli. Three hypotheses will be tested related to the objective. 1) Test the hypothesis that there are pools of Na,K-ATPase alpha beta heterodimers and NHE in both surface and intracellular membranes in renal cells, as well as pools of alpha and beta subunits that are not assembled as alpha beta heterodimers; determine whether these intracellular pools can be recruited to the plasma membrane, and test putative mediators of the redistribution. 2) Test the hypothesis that the rapid decrease in PT sodium transport that accompanies an acute increase in arterial pressure is due to decreased surface expression and/or activity of sodium pumps and NHE exchangers. Determine the time course and reversibility of the response, test putative mediators of the response, and whether the response is altered in hypertension models. 3) Test the hypothesis that the rate of production of one of the Na,K-ATPase subunits limits the pool size of active sodium pumps expressed in the PT plasma membrane, and can limit sodium transport. Determine the response to high salt diet in control and hypertensive rats and whether antisense to alpha or beta also limits the production of sodium pumps. Accomplishing our objective will contribute to our understanding of how alterations in these natriuretic responses may be mechanistically involved in the generation or maintenance of hypertension.