Alpha-Adrenoceptors in Vascular Wall Growth

α -1-肾上腺素能受体R)在细胞培养中，去甲肾上腺素（NE）激活可诱导平滑肌细胞（SMCs）和外基质成纤维细胞（AFBs）的生长。虽然α 1ar刺激已被认为有助于高血压壁肥大和纤维化，加剧动脉粥样硬化，并加重血管成形术后再狭窄，但在我们的研究之前，没有活体证据表明这是由于缺乏局部药物输送系统而产生的直接影响，而局部药物输送系统可以防止混淆的全身血流动力学作用。我们设计了一种新方法来克服这个问题。结合独特的器官培养方法、选择性α 1ar亚型拮抗剂和缺乏儿茶酚胺合成或特异性α 1ar亚型的敲除小鼠，将用于研究特异性α 1ar亚型对SMCs和afb的刺激对内膜病变生长、纤维化和血管重塑的重要作用。我们之前和初步的研究结果表明，在体外和体内，特定的al - AR亚型介导SMCs和AFBs的生长，并在很大程度上促进血管成形术后的再狭窄、向外肥厚重塑以及血管肥大和管腔丧失，从而导致肺动脉高压。目的完成这些模型中的工作，并将其扩展到高血压壁肥大。Aim II将通过免疫组织化学和western blot检测体内增殖、凋亡和迁移来确定NE如何加剧壁生长。目的III将验证损伤诱导神经突生长和增加NE含量和/或释放的假设。目的IV将确定介导NE的细胞内激酶途径。并验证其通过活性氧和/或egf受体转激活依赖途径进行的假设。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，并进行内膜-中膜和外膜的生化分析。本建议探讨

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.