NITRIC OXIDE SYNTHASE ISOFORMS IN RENAL MEDULLA AND BLOOD PRESSURE

我们实验室以前的数据表明， 在肾髓质的液体调节中起着关键作用， 电解质稳态和长期控制动脉压。 然而，这三个组成性表达的相对贡献 NOS亚型对肾小管和血管功能的调控 肾脏的这个区域是未知的。该项目将解决 认为NOS的三种亚型定位于不同的细胞， 肾髓质内的亚型，以及这些亚型产生的NO 作为肾小管或血管功能的自分泌控制器， 调节钠排泄，从而调节血压。的必然结果 这一假设是，选择性抑制不同的NOS同工型， 应该改变肾小管运输或髓血流量， 表达特定的同种型。这一假设将使用 一种独特的，综合的，生物学的方法。最初的一系列实验 将确定每种NOS同工型抑制剂的剂量， 输注到肾髓质中， 靶向异构体和对钠排泄和延髓的elevant作用 血流然后我们将利用慢性肾髓质间质 输注这些药物以确定每种NOS亚型的作用 (nNOS、iNOS和eNOS）对血压“盐敏感性”的影响， 以及它们在长期控制钠平衡和动脉 有意识的老鼠的压力同种型的慢性功能效应- 选择性抑制将与肾髓质NO的变化相关 使用新的微透析在清醒大鼠中测量浓度 技术和NOS蛋白的表达和酶活性 髓质最后，机制（管状或血管）， 肾髓质中各种NOS同工型的慢性抑制导致 钠潴留和高血压将通过检查 压力-尿钠关系，使用微穿刺的肾小管功能， 用激光多普勒血流仪和肾间质血流仪 使用植入的胶囊进行流体静压（RIHP）。这种独特的 生物化学、分子生物学和综合生物学技术应 提供了有关各种分布的重要新信息， 肾髓质中NOS的亚型及其重要性 同种型在调节髓质血流、肾小管功能和 长期控制动脉压。

Previous data from our laboratory indicate that nitric oxide (NO) produced in the renal medulla plays a critical role in the regulation of fluid and electrolyte homeostasis and the long term control of arterial pressure. However, the relative contribution of the three constitutively expressed isoforms of NOS to the control of renal tubular and vascular function in this region of the kidney is unknown. This project will address the hypothesis that the three isoforms of NOS are localized in different cell types within the renal medulla, and that the NO produced by these isoforms serves as an autocrine controller of tubular or vascular function to regulate sodium excretion and consequently blood pressure. A corollary of this hypothesis is that selective inhibition of different NOS isoforms should alter tubular transport or medullary blood flow depending on where a particular isoform is expressed. This hypothesis will be addressed using a unique, integrative, biological approach. The initial set of experiments will determine the dose of each of the NOS isoform inhibitors which when infused into the renal medullary interstitium selectively inhibits the targeted isoform and elicits effects on sodium excretion and medullary blood flow. We will then utilize chronic renal medullary interstitial infusion of these agents to determine the role of each of the NOS isoforms (nNOS, iNOS and eNOS) in influencing "salt-sensitivity" of blood pressure, and their role in the long term control of sodium balance and arterial pressure in conscious rats. The chronic functional effects of isoform- selective inhibition will be correlated with changes in renal medullary NO concentration measured in conscious rats using a new microdialysis technique and the expression of NOS proteins and enzyme activity in the medulla. Finally the mechanisms (either tubular or vascular) by which chronic inhibition of various NOS isoforms in the renal medulla leads to sodium retention and hypertension will be determined by examining the pressure-natriuresis relationship, tubular function using micropuncture, medullary blood flow using laser Doppler flowmetry and renal interstitial hydrostatic pressure (RIHP) using implanted capsules. This unique array of biochemical, molecular and integrative biological techniques should provide important new information regarding the distribution of various isoforms of NOS in the renal medulla and the critical importance of these isoforms in the regulation of medullary blood flow, tubular function and the long term control of arterial pressure.