Renal Vascular Reactivity in Hypertension

摘要 CD 38 ADP核糖基（ADPR）环化酶是一种膜结合酶，其产生已知的代谢物， 促进由Ryanodine受体（RyR）介导的小动脉平滑肌细胞中的Ca 2+动员。我们断定 肾脏CD 38是血管紧张素II（Ang II）诱导的高血压（AIH）发生的中心， 与野生型相比，CD 38缺陷小鼠表现出较不明显的肾血管收缩、Na+潴留和AIH。 (WT)小鼠目的1检验CD 38 ADPR环化酶参与AIH发展的假设， Ang II在CD 38-/-（整体遗传缺陷）小鼠中产生的高血压较WT小鼠更不明显。少 在靶向肾特异性部分敲除CD 38的WT小鼠中，也可预测重度高血压 通过siRNA诱导。AIH的严重程度是通过测量24小时动脉压（遥测）来确定的。 在慢性Ang II输注之前和期间，清醒的、不受约束的小鼠。还测量了24小时尿 排泄亚硝酸盐/硝酸盐和8-iso-PGF 2？，以评估一氧化氮（NO）的产生和氧化应激。CD38 将在肾小球前血管中定量mRNA和ADPR环化酶活性。AIM 2评估贡献 CD 38 ADPR环化酶对肾血管收缩的作用以及压力-尿钠排泄关系的改变， 啊。我们预测CD 38缺陷小鼠的肾脏在急性盐胁迫下会更快地排泄Na+。 在AIH发展过程中，与WT小鼠相比，排泄率在已建立的AIH中变得相似。 具有CD 38的整体敲除和肾特异性敲除的清醒和麻醉小鼠将被 在两个阶段进行评估。目的3评估CD 38是介导G- 蛋白偶联受体引起的Ca 2+信号转导涉及RyR和Ca 2+诱导的Ca 2+释放， 传入小动脉和肾血管收缩。我们预测，Ca 2+信号和血管 与WT小鼠相比，CD 38缺陷小鼠对血管收缩剂（Ang II、ET-1、TxA 2）的反应性减弱 在控制和AIH条件下。放射性配体结合的Scatchard分析将表征Ang II，ET-1， 以及肾微血管中TP受体亲和力和/或密度。我们的目标是确定一系列事件， 在高血压发展的早期或之前发生，因此更有可能是病因， 次要的，压力依赖的后果。联合基因靶向缺失CD 38、全局和肾脏- 具体而言，通过药理学抑制ADPR环化酶和RyR介导的Ca 2+释放， 重要的新信息是CD 38是介导Ca 2+信号传导的主要环化酶家族成员 肾微循环及其对肾血管收缩、Na+、Na+的长期调节作用 保持和发展AIH。成功地完成了我们的小说研究， 这将大大促进我们对细胞内Ca 2+信号传导的细胞/分子机制的理解， 肾微循环和调节肾血管反应性对健康和疾病的发生， 在球场上

ABSTRACT CD38 ADP ribosyl (ADPR) cyclase is a membrane-bound enzyme that produces metabolites known to promote Ca2+ mobilization mediated by ryanodine receptors (RyR) in arteriolar smooth muscle cells. We posit that renal CD38 is central to the development of angiotensin II (Ang II)-induced hypertension (AIH) and that CD38-deficient mice exhibit less pronounced renal vasoconstriction, Na+ retention and AIH than do wild-type (WT) mice. AIM 1 tests the hypothesis that CD38 ADPR cyclase participates in the development of AIH such that Ang II produces less pronounced hypertension in CD38-/- (global genetic deficiency) vs. WT mice. Less severe hypertension is also predicted in WT mice with targeted, renal-specific partial knockdown of CD38 induced by siRNA. The severity of AIH is determined by measuring 24-hr arterial pressure (telemetry) in conscious, unrestrained mice before and during chronic Ang II infusion. Also measured are 24 hr urinary excretion of nitrite/nitrate and 8-iso-PGF2¿ to assess nitric oxide (NO) production and oxidative stress. CD38 mRNA and ADPR cyclase activity will be quantified in preglomerular vessels. AIM 2 assesses the contribution of CD38 ADPR cyclase to renal vasoconstriction and the rightward shift in the pressure-natriuresis relation in AIH. We predict that the kidneys of CD38-deficient mice excrete Na+ more rapidly in response to an acute salt load than WT mice during development of AIH, with excretion rates becoming similar in established AIH. Conscious and anesthetized mice with global knockout and renal-specific knockdown of CD38 will be evaluated in both phases. AIM 3 evaluates the hypothesis that CD38 is the major ADPR cyclase mediating G- protein coupled receptor-elicited Ca2+ signaling involving RyR and Ca2+-induced Ca2+ release in isolated afferent arterioles and renal vasoconstriction in vivo. We predict that Ca2+ signaling and vascular responsiveness to vasoconstrictor agents (Ang II, ET-1, TxA2) are attenuated in CD38-deficient vs. WT mice during control and AIH conditions. Scatchard analysis of radioligand binding will characterize Ang II, ET-1, and TP receptor affinity and/or density in renal microvessels. Our goal is to identify a sequence of events that precede or occur early during the development of hypertension and thus are more likely to be causative than secondary, pressure-dependent consequences. Combining gene-targeted deletion of CD38, global and renal- specific, with pharmacological inhibition of ADPR cyclase and RyR-mediated Ca2+ release will provide important new information that CD38 is the primary cyclase family member mediating Ca2+ signaling in the renal microcirculation and its functional significance in long-term regulation of renal vasoconstriction, Na+ retention and the development of AIH. Successful completion of our novel studies of this underappreciated pathway will significantly advance our understanding of cellular/molecular mechanisms of Ca2+ signaling in the renal microcirculation and regulation of renal vascular reactivity in health and disease, making a major impact on the field.