Ang II and Norepinephrine in Cardiac Sympathetic Nerves

心脏交感神经中的 Ang II 和去甲肾上腺素

• 批准号: 7078069
• 负责人: ROBERTO LEVI
• 金额: $ 5.6万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7078069
• 关键词: Ang; II; Norepinephrine; Cardiac; Sympathetic

EXCEED THE SPACE PROVIDED. Pathologic release of norepinephrine (NE) from cardiac sympathetic nerve endings (cSNE) during myocardial ischemia leads to arrhythmias and death. The mechanisms responsible remain obscure. The overall objective of this grant is to address the important biological issue of whether a local cardiac renin-angiotensin system (RAS) plays a significant role in NE release from cSNE in myocardial ischemia. Our preliminary results demonstrate that cardiac mast cells are a source of extra-renal renin-like protein capable of cleaving angiotensinogen to ANG I. We hypothesize that degranulation of cardiac mast cells in ischemia is pivotal for local RAS activation and ANG II formation, proximal to cardiac SNE. In Specific Aim I, we will characterize the molecular identity of mast-cell derived renin in SNE isolated from rat, human, wild-type and mast cell deficient mouse hearts, and from the human mast cell line, HMC-1 cells. We will also investigate in ischemic cardiac models from guinea-pigs and humans, whether locally synthesized ANG II acts in a paracrine mode on AT1 receptors (AT1R) to elicit NE release. To confirm the role of mast cells in this cardiac RAS, parallel experiments will be conducted in mast-cell deficient mice. Because ANG II is a known stimulant of the Na+/H + exchanger (NHE),Iwe hypothesize that in ischemia, NHE stimulation by ANG II will lead to an increase in intracellular Na _, thereby triggering excessive NE release via the NE transporter. We will test this hypothesis in isolated cSNE expressing native ANG II receptors, and in human neuroblastoma cells transfected with cloned rat AT1A receptor (SH-SY5Y-AT_A). The signal transduction pathways mediating the effects of ANG II via AT1R on NE release will be studied in Specific Aim II. Pilot experiments demonstrate that ANG II stimulates the PLC-PKC pathway in cSNE, regulating NHE activity and NE release. Hence, we will study the roles of key elements of ANG II receptor-mediated signaling pathways involved in NHE activation and associated NE release. The experiments will focus on PLC, Cai, PKC, and calmodulin. The overall premise for conducting these experiments is that if we understand the physiological basis for the formation of ANG II in the heart, and how ANG II stimulates NE release, then we will also have identified targets that potentially can be exploited for therapies for ischemic arrhythmias and associated cardiac dysfunctions. PERFORMANCE SITE ========================================Section End===========================================

超出所提供的空间。在心肌缺血期间，去甲肾上腺素（NE）从心脏交感神经末梢（cSNE）的病理性释放导致心律失常和死亡。对此负责的机制仍不清楚。这项资助的总体目标是解决重要的生物学问题，即局部心脏肾素-血管紧张素系统（RAS）是否在心肌缺血时cSNE释放NE中起重要作用。我们的初步结果表明，心脏肥大细胞是一个来源的肾外肾素样蛋白能够切割血管紧张素原ANG I。我们推测，心肌肥大细胞在缺血中的脱粒是局部RAS激活和ANG II形成的关键，接近心脏SNE。在特定目标I中，我们将表征从大鼠、人、野生型和肥大细胞缺陷小鼠心脏以及从人肥大细胞系HMC-1细胞分离的SNE中肥大细胞来源的肾素的分子特性。我们还将研究在豚鼠和人类的缺血性心脏模型中，局部合成的ANG II是否以旁分泌模式作用于AT 1受体（AT 1 R）以引起NE释放。为了证实肥大细胞在心脏RAS中的作用，将在肥大细胞缺陷小鼠中进行平行实验。由于ANG Ⅱ是已知的Na+/H +交换器（NHE）的刺激剂，我们推测在缺血时，ANG Ⅱ刺激NHE将导致细胞内Na+增加，从而通过NE转运体触发过量NE释放。我们将在表达天然ANG II受体的分离的cSNE和用克隆的大鼠AT 1A受体（SH-SY 5 Y-AT_A）转染的人神经母细胞瘤细胞中检验这一假设。将在Specific Aim II中研究通过AT 1 R介导ANG II对NE释放影响的信号转导途径。初步实验表明，ANG II刺激cSNE中的PLC-PKC通路，调节NHE活性和NE释放。因此，我们将研究ANG II受体介导的信号通路的关键要素参与NHE激活和相关NE释放的作用。实验将集中在PLC，蔡，蛋白激酶C和钙调蛋白。进行这些实验的总体前提是，如果我们了解心脏中ANG II形成的生理基础，以及ANG II如何刺激NE释放，那么我们也将确定可能用于治疗缺血性心律失常和相关心脏功能障碍的靶点。性能现场=