Alpha-Adrenoceptors in Vascular Wall Growth

去甲肾上腺素(NE)激活α-1肾上腺素能受体(α1A.R)可诱导细胞培养中的平滑肌细胞(SMC)和外膜成纤维细胞(AFB)生长。尽管α1AR刺激被认为有助于高血压室壁肥厚和纤维化，加重动脉粥样硬化，并加重血管成形术后的再狭窄，但在我们的研究之前，没有体内证据表明这是直接影响，因为缺乏局部药物输送系统来防止混乱的全身血流动力学作用。我们设计了一种新的方法来克服这个问题。结合一种独特的器官培养方法、选择性的α1AR亚型拮抗剂和缺乏儿茶酚胺合成或特定α1AR亚型的基因敲除小鼠，将被用来研究刺激特定的α1AR亚型刺激SMC和AFB对血管内膜损伤生长、纤维化和血管重塑的重要作用。我们先前和初步的研究结果表明，在体外和体内，特定的AR亚型介导了SMC和AFBs的生长，并强烈地促进了血管成形术后的再狭窄、外向肥厚重塑和导致肺动脉高压的血管肥厚和管腔丧失。目的完成这些模型的研究工作，并将其推广到高血压性室壁肥厚。目的II将通过免疫组织化学和免疫印迹检测体内增殖、凋亡和迁移来确定去甲肾上腺素是如何加剧室壁生长的。目的III将验证损伤诱导轴突生长和NE含量和/或释放增加的假说。目的确定介导NE、S营养活性的细胞内激酶途径，并验证其通过依赖于活性氧和/或表皮生长因子受体反式激活途径的假说。这些Aim IV研究将使用正常和球囊损伤大鼠胸主动脉的器官培养，并对内中膜和外膜进行生化分析。这份提案审查了一个 新的基本概念，即儿茶酚胺是SMC和AFBs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疾病进展联系起来。这一结果可能为阿尔法-AR亚型特异性拮抗剂识别新的血管靶点，具有潜在的治疗应用。

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.