Angiotensin Adrenergic Interactions in the Kidney

描述(由申请人提供)： 项目摘要/摘要正常肾小球滤过率(GFR)伴随着钠重吸收(TNA)的平行变化。由于TNA是肾脏氧利用(QO2)的主要义务(&gt；80%)，QO2的变化或多或少与TNA同步。残肾或5/6肾切除(A/I)模型已被用作进展性慢性肾脏病(CKD)的有效实验范例。阻断血管紧张素II活性可显著预防或改善进行性肾功能丧失和肾小球硬化。我们观察了A/I肾形成一周后早期的代谢和分子变化。由TNA或QO2/TNA分解的QO2显着增加，导致早期A/I的低氧分压。联合应用血管紧张素转换酶抑制剂(CAP)和AT-1受体阻滞剂(LOS)(A/I+T1)可使QO2/TNA完全恢复正常。这些结果既不是血压降低的结果，因为三联疗法(A/I+T2)没有使QO2/TNA正常化，也不是伴随着赖氨酸(A/I+T3)阻断AII的GFR增加的结果。一些分子和酶在未治疗的A/I肾脏中过表达，包括NADPH氧化酶、血红素加氧酶-1(HO-1)，ERK1/2磷酸化和功能性一氧化氮活性降低。所有这些结果都通过阻断ALII而正常化，但不是通过血压和GFR的变化。低氧诱导因子-1α(HIF-1α)激活的多种因子，如血管内皮生长因子、GLUT-1和HO-1在未处理的5/6肾切除肾中表达。在具体目标#1中，我们将在所有组中检查几种处理的效果，以确定经AII阻断纠正的~60%的QO2/TNA增加的“PARS值”；假对照、A/I未处理、A/I+T1、A/I+T2和A/I+T3。这些包括：1)降低NO功能活性，2)AII诱导的肾脏胰岛素抵抗的作用(我们已经证明，急性胰岛素输注可以改善大约40-50%的QO2/TNA增加)，3)增加肾脏的糖异生，4)由于鸟氨酸脱羧酶抑制剂DFMO的生长刺激而引起的肾细胞增殖，5)NADPH氧化酶和ROS，6)用微穿刺法和显微注射技术降低钠的重吸收效率。我们将在肾大部切除术后4周进一步检查减少氧耗的手法对疾病进展的影响。在具体目标#2中，我们将重点研究A/I肾脏中激活的分子算法的系统生物学，假设NADPH氧化酶和HIF-1α构成导致其他分子、酶和细胞周期蛋白/细胞周期蛋白/细胞周期蛋白I激活的主要关键枢纽，这些分子对细胞增殖和潜在的肾脏纤维化至关重要。我们将研究载脂蛋白对NADPH氧化酶的抑制作用。我们将抑制(棘霉素和YC-1)和诱导HIF-1α(CoCl2和DMOG)，以确定对下游分子事件的复杂净效应。我们还将在4周时检查NADPH氧化酶和HIF-1α的操作对疾病进展的影响。 公共卫生相关性： 项目简介有2000-4000万美国人患有慢性肾脏疾病(CKD)，这种疾病对退伍军人人口的影响非常显著。慢性肾脏病不仅是进展性的，在许多情况下是终末期肾病，需要人工肾治疗或肾移植，而且极大地促进了心脏和循环系统疾病的极高发病率。用同时降低血压的药物阻断肾素-血管紧张素系统已被证明是有好处的，因为它们减缓了肾功能进行性丧失的速度。在慢性肾脏病模型中，两种降低肾脏血管紧张素效应的药物联合治疗可使因氯化钠重吸收而产生的耗氧量正常化。我们将确定导致氧耗增加的多种因素，以及阻断血管紧张素使氧耗恢复正常的原因，并确定参与这一过程的分子和酶。

DESCRIPTION (provided by applicant): Project Summary/Abstract In the normal kidney glomerular filtration rate (GFR) is accompanied by parallel changes in Na reabsorption (TNa). Since TNa constitutes the major obligation for kidney oxygen utilization (QO2) (>80%) QO2 changes more or less in parallel with TNa. The remnant kidney or 5/6th nephrectomy (A/I) model has been used as a valid experimental example of progressive chronic kidney disease (CKD). Blockade of angiotensin II activity greatly prevents or ameliorates progressive loss of kidney function and glomerulosclerosis. We have examined the metabolic and molecular changes in the early phases of the A/I kidney one week after creation. QO2 factored by TNa or QO2/TNa is increased markedly leading to low oxygen tension in the A/I at this earlier stage. Combined AII blockade with ACE inhibitor (CAP) and AT-1 receptor blocker (LOS) (A/I + T1) totally normalizes the QO2/TNa. These findings were not the result of either the reduction of blood pressure since triple therapy (A/I + T2) did not normalize QO2/TNa nor did the increase in GFR that accompanies AII blockade by administration of lysine (A/I + T3) Several molecules and enzymes were overexpressed in the untreated A/I kidney including NADPH oxidase, heme-oxygenase-1 (HO-1),, and ERK 1/2 phosphorylation and functional nitric oxide activity was decreased. All of these findings were normalized by AII blockade but not by changes in blood pressure and GFR. Several factors activated by hypoxia inducible factor-1 alpha (HIF-1 alpha) e.g., VEGF, GLUT-1 and HO-1 were expressed in the untreated 5/6th nephrectomy kidney. In Specific Aim #1 we will examine in all groups the effects of several treatments to define the "pars value" of contributions to the ~60% increase in QO2/TNa corrected by AII blockade; sham control, A/I untreated, A/I + T1, A/I + T2 and A/I + T3. These include 1) reduced NO functional activity, 2) role of AII induced insulin resistance in the kidney (we have shown that acute insulin infusion ameliorates approximately 40-50% of the increase in QO2/TNa), 3) increased kidney gluconeogenesis, 4) kidney cell proliferation due to growth stimuli using DFMO, inhibitor of ornithine decarboxylase, 5) NADPH oxidase and ROS, 6) decreased efficiency of Na reabsorption using micropuncture and microinjection techniques. We will examine further the effects of maneuvers that reduce oxygen consumption on disease progression at 4 weeks after subtotal nephrectomy. In Specific Aim #2 we will focus upon the systems biology of the molecular algorithm of activation in the A/I kidney with the hypothesis that NADPH oxidase and HIF-1 alpha constitute the major critical hubs leading to activation of other molecules, enzymes and cyclins/CKI important to cell proliferation and potential kidney fibrosis. We will examine the effects of NADPH oxidase inhibition with apocycnin. We will both inhibit (echinomycin and YC-1) and induce HIF-1 alpha (CoCl2 and DMOG) to determine complex net effects on downstream molecular events. We will also examine the effects of manipulation of NADPH oxidase and HIF-1 alpha on progression of disease at 4 weeks. PUBLIC HEALTH RELEVANCE: Project Narrative There are 20-40 million Americans with chronic kidney disease (CKD) and the impact of this disease on the Veterans population is very significant. CKD is not only progressive, in many cases to end stage kidney disease requiring artificial kidney treatments or kidney transplantation, but also contributes greatly to the very high incidence of heart and circulatory disease. Blockade of the renin-angiotensin system with drugs that also lower blood pressure has been shown of benefit in that they slow the rate of progressive loss of kidney function. Combined treatment with two agents that decrease angiotensin effects in the kidney normalizes oxygen consumption factored by NaCl reabsorption in a model of CKD. We will determine the multiple contributing factors leading to increased oxygen consumption and the reasons why blockade of angiotensin restores oxygen consumption to normal and define the molecules and enzymes that are involved in this process.