Alpha-Adrenoceptors in Vascular Wall Growth

去甲肾上腺素（NE）激活α-1-肾上腺素能受体（α 1A.R）可诱导细胞培养物中平滑肌细胞（SMC）和外膜成纤维细胞（AFB）的生长。尽管已经提出α 1AR刺激有助于高血压壁肥大和纤维化，加剧动脉粥样硬化，并使血管成形术后再狭窄恶化，但直到我们的研究，由于缺乏可以防止混淆全身血流动力学作用的局部药物递送系统，因此没有体内证据表明这是直接作用。我们设计了一种新的方法来克服这个问题。本研究将结合独特的器官培养方法、选择性α 1 AR亚型拮抗剂和缺乏儿茶酚胺合成或特定α 1 AR亚型的敲除小鼠，用于研究刺激SMC和AFB上特异性α 1 AR亚型对内膜病变生长、纤维化和血管重塑的重要作用。我们先前的和初步的结果已经证明，特定的α 1 AR亚型介导SMC和AFB在体外和体内的生长，并强烈地促进血管成形术后的再狭窄、向外肥厚性重构和导致肺动脉高压的血管肥大和管腔损失。目的完善这些模型，并将其推广到高血压室壁肥厚。目的II将通过免疫组化和蛋白质印迹法在体内检测细胞增殖、凋亡和迁移来确定NE是如何加剧细胞壁生长的。目的III将测试损伤诱导神经突生长和增加NE含量和/或释放的假设。目的研究细胞内激酶通路介导NE？的营养活性和测试的假设，它通过活性氧物种和/或EGF受体反式激活依赖的途径进行。这些目标IV研究将使用正常和球囊损伤大鼠胸主动脉的器官培养物，并进行内膜-中膜和外膜的生化测定。本提案审查了 新的基本概念，即，儿茶酚胺是SMC和AFB的重要营养因子。我们认为这种机制将交感神经系统与适应性血管重塑和病理性疾病进展联系起来。这些结果可能会确定新的血管靶点，为具有潜在治疗应用的血管-AR亚型特异性拮抗剂。

Alpha-1-adrenergic receptor (alpha 1A.R) activation by norepinephrine (NE) induces growth of smooth muscle cells (SMCs) and adventitial fibroblasts (AFBs) in cell culture. Although alpha1AR stimulation has been proposed to contribute to hypertensive wall hypertrophy and fibrosis, exacerbate atherosclerosis, and to worsen restenosis after angioplasty, until our studies there was no in vivo evidence that this was from a direct effect because of absence of local drug delivery systems that could prevent confounding systemic hemodynamic actions. We have devised a novel method that overcomes this problem. This, together with a unique organ culture method, selective alpha1AR subtype antagonists, and knockout mice devoid of catecholamine synthesis or specific alpha1AR subtypes, will be used to investigate the hvnothesis that stimulation of a snecific allpha1AR subtvne on SMCs and AFBs contribute importantlv to intimal lesion growth, fibrosis and vascular remodeling. Our previous and preliminary results have demonstrated that specific al AR subtypes mediate growth of SMCs and AFBs in vitro and in vivo, and strongly contribute to restenosis after angioplasty, outward hypertrophic remodeling and the vascular hypertrophy and lumen loss that causes pulmonary hypertension. Aim I will complete the work in these models, and extend it to hypertensive wall hypertrophy. Aim II will determine how NE exacerbates wall growth by in vivo examination of proliferation, apoptosis, and migration with immunohistochemistry and western blot. Aim III will test the hypothesis that injury induces neurite outgrowth and increased NE content and/or release. Aim IV will identify the intracellular kinase pathway mediating NE?s trophic activity and test the hypothesis that it proceeds through reactive oxygen species-and/or EGF-receptor transactivation-dependent pathways. These Aim IV studies will use organ culture of normal and balloon-injured rat thoracic aorta, with biochemical assays of intima-media and adventitia. This proposal examines a new fundamental concept, i.e., that catecholamines are important trophic factors for SMCs and AFBs. We propose that this mechanism links the sympathetic nervous system to adaptive vascular remodeling and to pathological disease progression. The results may identify novel vascular targets for alphal-AR subtype-specific antagonists with potential therapeutic application.