Renal Vascular Reactivity in Hypertension

摘要 CD38-ADP核糖(ADPR)环化酶是一种膜结合酶，可产生已知的 促进微动脉平滑肌细胞兰尼定受体(RyR)介导的钙动员。我们假设 肾脏CD38在血管紧张素II(Ang II)诱导的高血压(AIH)的发生发展中起中心作用 与野生型相比，CD38缺陷小鼠的肾脏血管收缩、Na+滞留和AIH较少 (WT)小鼠。目的1验证CD38 ADPR环化酶参与AIH发病的假说。 与WT小鼠相比，Ang II在CD38-/-(全球遗传缺陷)小鼠中产生的高血压不那么明显。较少 靶向、肾脏特异性部分敲除CD38的WT小鼠也可预测严重高血压 由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 清醒、无拘束的小鼠，在慢性血管紧张素Ⅱ输注之前和期间。还测量了24小时的尿量 排泄亚硝酸盐/硝酸盐和8-iso-PGF2，以评估一氧化氮(NO)的产生和氧化应激。CD38 肾小球前血管中的mRNA和ADPR循环酶活性将被量化。目标2评估贡献 CD38-ADPR环化酶与肾血管收缩及血压-尿钠关系右移 啊哈。我们预测，CD38缺陷小鼠的肾脏对急性盐的反应会更快地排泄Na+ 在AIH的发育过程中，与WT小鼠相比，AIH的排泄率变得相似。 具有CD38全局敲除和肾脏特异性敲除的清醒和麻醉小鼠将被 在两个阶段都进行了评估。目的3评估CD38是主要的ADPR环化酶介导G- RyR参与的蛋白偶联受体诱导的钙信号转导及钙离子诱导的钙释放 体内传入小动脉和肾血管收缩。我们预测，钙信号和血管 CD38缺陷小鼠对血管紧张剂(Ang II、ET-1、TXA2)的反应性减弱 在对照和AIH条件下。放射性配基结合的Scatchard分析将表征Ang II，ET-1， 肾微血管TP受体亲和力和/或密度。我们的目标是确定一系列事件， 先于或发生在高血压发展的早期，因此更有可能是引起高血压的 次要的、依赖压力的后果。结合基因靶向缺失CD38，全局和肾脏- 特异性的，通过药物抑制ADPR环化酶和RyR介导的钙释放将提供 重要的新信息CD38是介导细胞内钙信号转导的主要周期酶家族成员 肾微循环及其在肾血管收缩长期调节中的功能意义 AIH的保留和发展。我们成功完成了对这部小说的研究，但没有得到足够的重视 这一途径将极大地促进我们对钙离子信号转导机制的理解。 肾微循环和调节肾血管反应性在健康和疾病中产生重大影响 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.