XANTHINE OXIDASE MODULATION OF CELL OXIDANT PRODUCTION

描述：（改编自申请人的摘要）：内皮作为 维持血管内环境稳定的关键成分。的改变 内皮细胞产生的氧化剂导致血管缺陷 功能，并与多种血管疾病的发病机制有关。 然而，增强血管细胞氧化剂产生的组织来源和 氧化剂作用的位点还没有确定。最近， a）循环黄嘌呤氧化酶的血浆水平升高 在多种疾病过程中的活性（败血症、高胆固醇血症、 肝移植）和B）黄嘌呤氧化酶特异性 与内皮细胞结合，导致细胞内黄嘌呤氧化酶增加 活性提供了潜在的机制，通过该机制，非内皮细胞来源的 黄嘌呤氧化酶可能有助于内皮细胞氧化剂的产生。而 增加超氧化物的产生可以通过以下方式降低一氧化氮的生物利用度： 由于其与一氧化氮的反应， 次级氧化剂，超氧化物和其他细胞氧化剂的潜力， 直接改变内皮型一氧化氮合酶的活性， 充分探索。从这一理解的基础上，可以假设， 细胞相关黄嘌呤氧化酶的增加调节内皮依赖性 血管功能为了解决这一假设，以下具体目标将 1）表征血管细胞与循环细胞的相互作用， 黄嘌呤氧化酶细胞结合和摄取的动力学 将测定黄嘌呤氧化酶/脱氢酶。此外，黄嘌呤 将在体内确定氧化酶循环和最终组织分布。 2)探讨黄嘌呤氧化酶衍生产物（反应性）升高的影响 尿酸）对内皮细胞一氧化氮表达和活性的影响 合成酶黄嘌呤氧化酶对转录和翻译的影响 还将确定内皮型一氧化氮合酶。血管 增加的黄嘌呤氧化酶活性的功能后果也将是 测定在成功实现拟议目标后，a） 黄嘌呤氧化酶对内皮细胞氧化剂产生的贡献将是 更好地定义，B）详细的机械信息将可用于 特定氧化途径的存在、反应和调节， 调节内皮型一氧化氮合酶的表达和活性，和c）新的 将获得前瞻性地设计机制导向的洞察力， 药理学策略

DESCRIPTION: (Adapted from the Applicant's Abstract): The endothelium serves as a critical component in the maintenance of vascular homeostasis. Alterations in endothelial cell production of oxidants contribute to defective vascular function and are implicated in the pathogenesis of diverse vascular diseases. However, the tissue sources of enhanced vascular cell oxidant production and the sites of oxidant action have not been determined with certainty. Recently, recognition of a) elevated plasma levels of circulating xanthine oxidase activity in diverse disease processes (sepsis, hypercholesterolemia, post- liver transplantation) and b) the ability of xanthine oxidase to specifically bind to endothelium with resultant increases in intracellular xanthine oxidase activity provide potential mechanism(s) by which non-endothelial cell-derived xanthine oxidase could contribute to endothelial oxidant production. While enhanced production of superoxide can diminish nitric oxide bioavailability by virtue of its reaction with nitric oxide and thus, concomitantly yield secondary oxidants, the potential for superoxide and other cellular oxidants to directly modify the activity of endothelial nitric oxide synthase has not been fully explored. From this foundation of understanding, it is hypothesized that increases in cell-associated xanthine oxidase modulate endothelial-dependent vascular function. To address this hypothesis, the following Specific Aims will be pursued: 1) Characterize vascular cell interactions with circulating xanthine oxidase. The kinetics of cell binding and uptake of circulating xanthine oxidase/dehydrogenase will be determined. In addition, xanthine oxidase circulating and ultimate tissue distribution will be defined in vivo. 2) Explore the impact of elevated xanthine oxidase-derived products (reactive species, uric acid) on expression and activity of endothelial nitric oxide synthase. The effects of xanthine oxidase on transcription and translation of endothelial nitric oxide synthase will be ascertained as well. The vascular functional consequences of increased xanthine oxidase activity will also be determined. Upon successful completion of the proposed aims, a) the contribution of xanthine oxidase to endothelial cell oxidant production will be better defined, b) detailed mechanistic information will be available regarding the presence, reactions and regulation of specific oxidative pathways that modulate endothelial nitric oxide synthase expression and activity and c) new insight will be gained for prospectively devising mechanism-directed pharmacologic strategies.