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: 7012200
• 负责人: ROBERTO LEVI
• 金额: $ 49.22万
• 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/7012200
• 关键词: angiotensin II; arrhythmia; biological signal transduction; calcium flux; calmodulin; cell line; clinical research; exocytosis; genetically modified animals; guinea pigs; heart cell; hormone regulation /control mechanism; human tissue; laboratory mouse; mast cell; myocardial ischemia /hypoxia; neurotransmitter receptor; neurotransmitter transport; norepinephrine; phospholipase C; protein kinase C; receptor expression; renin angiotensin system; sodium hydrogen exchanger; sympathetic nervous system; tissue /cell culture

DESCRIPTION (provided by applicant): In myocardial ischemia, pathologic release of norepinephrine (NE) from sympathetic nerves 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 renin-angiotensin system (RAS) plays a significant role in exacerbating NE release in myocardial ischemia. Our preliminary results demonstrate that cardiac mast cells are a novel source of renin, the rate-limiting enzyme responsible for initiating ANG n formation. We hypothesize that degranulation of cardiac mast cells, as occurs in ischemia, is pivotal for activation of local RAS and ANG II formation in the proximity of neuronal ATi receptors (ATiR). In Specific Aim I, we will characterize mast-cell renin from congenic controls (CC) of c-Kit knock out (KO) mice, and from cultured human mast cells (HMC-1). We will also investigate in normoxic and ischemic cardiac models from guinea-pigs, and CC and KO mice, whether locally synthesized ANG n from mast-cell-derived renin activates neuronal ATiR to elicit NE release and reperfusion arrhythmias. We have already ascertained in a cultured-cell model of ischemic sympathetic nerves, that exogenous ANG n stimulates neuronal Na+/H^ exchange (NHE) leading to excessive carrier-mediated NE release. Thus, in Specific Aim n we will study, in human neuroblastoma cells transfected with the cloned rat ATjA receptor (SH-SYSY-ATu), the signal transduction of this ANG H-mediated NHE stimulation. Experiments in SH-SYSY-ATiA cells demonstrate that stimulation of NHE and carrier-mediated NE release by AT)R activation occurs via a Ca +-dependent pathway. Accordingly, our investigation will focus on elucidating the role of PLC, Ca2+, PKC, and calmodulin in this Ca2+-dependent pathway. The overall premise of these experiments is that if we understand the patho-physiological basis for the formation of ANG n in the ischemic heart, and how ANG II exacerbates NE release, then we will also have identified potential therapeutic targets to alleviate ischemic arrhythmias and associated cardiac dysfunctions.

描述（由申请人提供）：在心肌缺血中，交感神经病理性释放去甲肾上腺素（NE）会导致心律失常和死亡。 负责的机制仍然不清楚。 该资助的总体目标是解决局部肾素-血管紧张素系统（RAS）是否在加剧心肌缺血中的 NE 释放中发挥重要作用的重要生物学问题。 我们的初步结果表明，心脏肥大细胞是肾素的新来源，肾素是负责启动 ANG n 形成的限速酶。 我们假设心脏肥大细胞的脱颗粒（如缺血时发生的那样）对于激活神经元 ATi 受体 (ATiR) 附近的局部 RAS 和 ANG II 形成至关重要。 在特定目标 I 中，我们将表征来自 c-Kit 敲除 (KO) 小鼠的同源对照 (CC) 和培养的人类肥大细胞 (HMC-1) 的肥大细胞肾素。 我们还将在豚鼠、CC 和 KO 小鼠的常氧和缺血心脏模型中研究来自肥大细胞源性肾素的局部合成的 ANG n 是否会激活神经元 ATiR 以引起 NE 释放和再灌注心律失常。 我们已经在缺血性交感神经的培养细胞模型中确定，外源性 ANG n 刺激神经元 Na+/H^ 交换（NHE），导致载体介导的 NE 过度释放。 因此，在特定目标中，我们将研究在用克隆的大鼠 ATjA 受体 (SH-SYSY-ATu) 转染的人神经母细胞瘤细胞中，这种 ANG H 介导的 NHE 刺激的信号转导。 SH-SYSY-ATiA 细胞中的实验表明，AT)R 激活对 NHE 和载体介导的 NE 释放的刺激是通过 Ca + 依赖性途径发生的。 因此，我们的研究将集中于阐明 PLC、Ca2+、PKC 和钙调蛋白在这一 Ca2+ 依赖性途径中的作用。 这些实验的总体前提是，如果我们了解缺血心脏中 ANG n 形成的病理生理学基础，以及 ANG II 如何加剧 NE 释放，那么我们还将确定减轻缺血性心律失常和相关心功能障碍的潜在治疗靶点。