Renal oxygenation, oxidative stress and nitric oxide

氧化应激意味着活性氧（ROS）的过量产生或代谢减少。参与血管和肾脏稳态的主要活性氧是超氧化物。在本研究中，过量的超氧化物是由慢性血管紧张素II治疗通过刺激氧化酶（如NADPH氧化酶）和过量的氧气（通过线粒体细胞色素c转化）产生的。超氧化物与一氧化氮（NO）发生反应，从而降低其生物活性。一氧化氮是一种有效的血管扩张剂，可调节肾血流量和肾小球滤过率。我们将研究5种蛋白质在产生关键成分中的作用，这些关键成分决定了氧化应激在肾功能调节中的作用。我们将在两个系列的生理研究中使用基因缺失的小鼠来评估5个关键蛋白的作用。在Specific Aim 1中，我们将在5个不同的转基因小鼠品系中评估慢性血管紧张素II治疗后氧化应激对肾脏氧气使用和肾功能的影响。对内皮型一氧化氮合酶（eNOS）、神经元型一氧化氮合酶（nNOS）、NAD(P)H氧化酶p47/phox亚基、细胞外超氧化物歧化酶（EC-SOD）和多巴胺-5受体（D5-R）基因进行研究。我们将验证在血管紧张素II引起的氧化应激过程中，小鼠肾氧消耗相对于钠运输增加，肾组织氧减少的假设。这些影响是由于缺乏一氧化氮，过量的超氧化物减少了一氧化氮，过量的超氧化物是由NADPH氧化酶活性增加和EC-SOD和/或D5-R抗氧化活性降低共同产生的。在特异性目的2中，我们将测量一氧化氮的反应性，并将通过单肾单位GFR变化在肾单位灌注一氧化氮供体时进行评估。我们将验证肾皮质慢性氧化应激降低JGA NO反应性的假设。在Specific Aim 3中，我们将在类似的实验中测试高氧引起的急性氧化应激对肾小球旁器官NO反应性的影响。这些研究的结果应该确定氧化应激和氧合在一氧化氮调节肾功能中的作用。

Oxidative stress implies excess production or reduced metabolism of reactive oxygen species (ROS). A major ROS involved in vascular and renal homeostasis is superoxide. In this study excess superoxide is generated by chronic angiotensin II treatment via stimulation of oxidase enzymes, such as NADPH oxidase and by excessive oxygen, via mitochondria cytochrome c conversion. Superoxide reacts with nitric oxide (NO), thus reducing its biological activity. NO, a potent vasodilator regulates renal blood flow and glomerular filtration rate. We will study the roles of 5 proteins in the generation of key components that define the role of oxidative stress in the regulation of renal function. We will evaluate the roles of 5 key proteins by using mice with gene deletions in two series of physiological studies. In Specific Aim 1, we will assess the impact of oxidative stress on the kidney's usage of oxygen and renal function after chronic angiotensin II treatment, in 5 separate strains of genetically altered mice. Genes for endothelial nitric oxide synthase (eNOS), neuronal NOS (nNOS), the p47/phox subu7nit of NAD(P)H oxidase, extracellular superoxide dismutase (EC-SOD) and dopamine-5 receptor (D5-R) will be studied. We will test the hypothesis that renal oxygen consumption relative to sodium transported is increased and renal tissue oxygen is decreased in mice during oxidative stress generated by angiotensin II. These effects are due to the lack of NO which is reduced by excess superoxide, generated by the combination of increased activity of NADPH oxidase and reduced antioxidant activity of EC-SOD and/or D5-R. In Specific Aim 2, we will measure the NO responsiveness will be assessed by the single nephron GFR change during perfusion of the renal nephron with a NO donor. We will test the hypothesis that chronic oxidative stress in the renal cortex reduces NO responsiveness in the JGA. In Specific Aim 3, we will test the effect of acute oxidative stress generated by hyperoxia on NO responsiveness in the juxtaglomerular apparatus, in similar experiments. Results from these studies should identify the role of oxidative stress and oxygenation on nitric oxide regulation of renal function.