NITRIC OXIDE SYNTHASE ISOFORMS IN RENAL MEDULLA AND BLOOD PRESSURE

我们实验室以前的数据表明，一氧化氮(NO)产生 在肾髓质中起着关键的调节液体和 电解质平衡和动脉压的长期控制。 然而，这三个因素的相对贡献被结构性地表达出来 一氧化氮合酶亚型对大鼠肾小管和血管功能的调控作用 肾脏的这一区域是未知的。该项目将解决 一氧化氮合酶三种亚型定位于不同细胞的假说 肾髓质内的类型，以及这些异构体产生的NO 作为肾小管或血管功能的自分泌控制器 调节钠的排泄，从而调节血压。的推论 这一假说是选择性抑制不同的一氧化氮合酶亚型 应根据位置改变肾小管运输或髓质血流 表达了一种特定的异构体。这一假设将通过以下方式解决： 一种独特的、综合的、生物学的方法。最初的一系列实验 将确定每种一氧化氮合酶异构体抑制剂的剂量 肾髓质内灌注选择性抑制血管紧张素转换酶 靶向异构体及其对钠排泄和髓质的影响 血液流动。然后我们将利用慢性肾髓质间质 输注这些药物以确定每一种一氧化氮合酶亚型的作用 (nNOS、iNOS和eNOS)在影响血压的“盐敏感性”中， 以及它们在长期控制钠平衡和动脉血中的作用 清醒大鼠的压力。异构体的慢性功能效应- 选择性抑制与肾髓质一氧化氮的变化相关 用一种新的微透析法测量清醒大鼠的血药浓度 技术及一氧化氮合酶蛋白表达和酶活性的研究 延髓。最后，这些机制(无论是管状的还是管状的) 肾髓质中各种一氧化氮合酶亚型的慢性抑制导致 钠滞留和高血压将通过检查 血压-尿钠关系，微创肾小管功能， 激光多普勒血流仪与肾间质的髓内血流 使用植入胶囊的静水压力(RIHP)。这一独特的阵列 生化、分子和综合生物技术应该 提供重要的新信息，关于各种 肾髓质中一氧化氮合酶的异构体及其重要意义 髓血流量、肾小管功能和肾小管功能调节中的异构体 对动脉压的长期控制。

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.