Renal oxygenation, oxidative stress and nitric oxide

氧化应激意味着活性氧物种(ROS)的过度产生或代谢减少。参与血管和肾脏动态平衡的主要ROS是超氧化物歧化酶。在这项研究中，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转换而产生的。超氧化物与一氧化氮(NO)反应，从而降低其生物活性。不，一种有效的血管扩张剂可以调节肾血流量和肾小球滤过率。我们将研究5种蛋白质在关键成分的产生中的作用，这些成分定义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学研究中，通过使用基因缺失的小鼠来评估5个关键蛋白的作用。在具体目标1中，我们将评估氧化应激对慢性血管紧张素II治疗后肾脏氧气利用和肾功能的影响，在5个不同品系的基因改变的小鼠中。将研究内皮型一氧化氮合酶(ENOS)、神经型一氧化氮合酶(NNOS)、NAD(P)H氧化酶的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)的基因。我们将验证这一假设，即在血管紧张素II产生的氧化应激期间，小鼠肾脏相对于钠转运的氧耗增加，肾组织氧减少。这些影响是由于缺乏NO，而过量的超氧化物歧化是由于NADPH氧化酶活性增加和EC-SOD和/或D5-R抗氧化活性降低所产生的。在特定的目标2中，我们将通过用NO供体灌流肾单位时单个肾单位GFR的变化来评估NO的反应性。我们将检验这样一种假设，即肾脏皮质的慢性氧化应激会降低JGA中的NO反应性。在具体目标3中，我们将在类似的实验中测试高氧产生的急性氧化应激对肾小球旁器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.