The Role of Extracellular Superoxide Dismutase in Modulation of Hypertension

在过去的资助周期中，我们的研究强调了NAD（P）H氧化酶作为活性氧来源的重要性，并证实了它在血管紧张素II引起的高血压中起着至关重要的作用。此外，我们还发现，细胞外超氧化物歧化酶（ecSOD）似乎在血管氧化应激增加相关的疾病中发挥重要的代偿作用，例如在血管紧张素H诱导的高血压和两种转基因小鼠模型中（p22 phox或nox过表达的小鼠1）。 最近，我们发现缺乏ecSOD的小鼠，ecSOD小鼠，血管紧张素II输注引起的高血压显著增强，再次支持ecSOD在调节氧化应激和高血压中的关键作用。在目前的研究中，我们计划进一步了解这种酶的调节以及它如何调节血压。在目标1中，我们将研究假设H2 O2是负责增加ecSOD响应血管紧张素II。为了实现这一点，我们将在存在或不存在PEG-SOD或PEG-过氧化氢酶的情况下用血管紧张素II处理培养的血管平滑肌细胞。我们还将研究 来自p47 phox-/-小鼠的p47 phox缺陷的血管平滑肌细胞和过表达过氧化氢酶的细胞（Tg catvsmc小鼠）。在体内，我们将检查血管紧张素II的能力，增加ecSOD表达p47 phox-/-小鼠和Tg catvsmc小鼠。我们预计，ecSOD的表达不会增加p47 phox-/-小鼠或Tg catvsmc小鼠。在目标2和3中，我们将研究血管紧张素II在ecSOD -/-小鼠中引起高血压增强的机制。在目的2中，我们将检查血管紧张素II对肾功能的影响。 在野生型和ecSOD /小鼠中的钠排泄，并检查无钠饮食对这些动物血压的影响。在目标3中，我们将利用我们最近创建的小鼠，其将允许血管平滑肌特异性缺失ecSOD，并检查血管紧张素II对这些小鼠的血压和肾钠排泄的影响。还将在这些小鼠中研究血管紧张素II对血管反应性、超氧化物产生和一氧化氮生物利用度的影响。这一目标将使我们能够了解血管与非血管来源的ecSOD在调节血压和血管张力中的相对重要性。最后，在目的4中，我们将研究在过表达NAD（P）H氧化酶亚基p22 phox的小鼠中缺失ecSOD的影响。我们在过去的资助期间创建的这些转基因小鼠，血管自由基氧产生适度增加，ecSOD表达增加3倍。我们推测，在这些小鼠中ecSOD的消除将导致高血压表型与血管自由基氧产生显着增加。总的来说，这些研究应该进一步了解血管氧化应激是如何在体内调制，特别是提供新的信息，在这个过程中的ecSOD的重要性。

During the past funding cycle, our research has emphasized the importance of the NAD(P)H oxidase as a source of reactive oxygen species and confirmed that it plays a crucial role in the hypertension caused by angiotensin II. In addition, we have shown that the extracellular superoxide dismutase (ecSOD) seems to play an important compensatory role in conditions associated with increased vascular oxidant stress, for example in angiotensin H-induced hypertension and in two transgenic mouse models tmice overexpressing either p22 phox or nox1). Very recently, we have found that mice lacking ecSOD, ecSOD mice, the hypertension caused by angiotensin II infusion is dramatically enhanced, again supporting a critical role of the ecSOD in modulating oxidant stress and hypertension. In the present studies, we plan to gain further insight into regulation of this enzyme and how it modulates blood pressure. In aim 1, we will examine the hypothesis that H2O2 is responsible for the increase in ecSOD in response to angiotensin II. To accomplish this, we will treat vascular smooth muscle cells in culture with angiotensin II in the presence or absence of PEG-SOD or PEG-catalase. We will also study vascular smooth muscle cells that are deficient in p47 phox from p47 phox-/-mice and cells overexpressing catalase (Tg catvsmc mice). In vivo, we will examine the ability of angiotensin II to increase ecSOD expression in p47 phox-/- mice and Tg catvsmc mice. We anticipate that ecSOD expression will not be increased in p47 phox-/- mice or in Tg catvsmc mice. In aims 2 and 3, we will examine mechanisms responsible for the augmented hypertension caused by angiotensin II in the ecSOD -/- mice. In aim 2, we will examine the effect of angiotensin II on renal sodium excretion in wild-type and ecSOD / mice and examine the effect of a sodium free diet on blood pressure in these animals. In aim 3, we will make use of a mouse that we have recently created that will allow vascular smooth muscle specific deletion of ecSOD and examine the effect of angiotensin II on blood pressure and renal sodium excretion in these mice. The effect of angiotensin II on vascular reactivity, superoxide production and nitric oxide bioavailability will be studied in these mice as well. This aim will allow us to understand the relative importance of vascular vs. non-vascular sources of ecSOD in modulation of blood pressure and vascular tone. Finally, in aim 4, we will study the effect of deletion of ecSOD in mice overexpressing the NAD(P)H oxidase subunit p22 phox. These transgenic mice, which we created during the past funding period, have a modest increase in vascular free radical oxygen production and a 3-fold increase in ecSOD expression. We hypothesize that elimination of ecSOD in these mice will result in a hypertensive phenotype with a marked increase in vascular free radical oxygen production. Overall, these studies should further our knowledge of how vascular oxidant stress is modulated in vivo and in particular provide new information regarding the importance of the ecSOD in this process.