NITRIC OXIDE INHIBITION OF APO-B-MEDIATED LDL OXIDATION

在这项新的FIRCA申请中描述的实验目标解决了西化国家发病率和死亡率的主要来源--动脉粥样硬化的基本机制。它们还为进一步扩大由阿拉巴马大学伯明翰医学院和乌拉圭蒙得维的亚雷布利卡大学美第奇学院的研究人员共享的在自由基生物学和医学方面的互惠合作研究和培训活动奠定了基础。具体地说，母公司赠款的主题-一氧化氮介导膜脂和脂蛋白中的抗氧化作用-将向一个新的重要方向扩展，解决-NO可以通过与基于蛋白质的自由基相互作用发挥这些作用的新概念。假设-NO在调节低密度脂蛋白氧化中起关键作用：a)易于扩散到低密度脂蛋白颗粒的表面和核心，从而代表低密度脂蛋白亲脂核心中的主要抗氧化剂物种；以及b)扩散控制与以apoB-100为中心的氨基酸自由基的反应，从而抑制脂质和蛋白质的氧化反应。此外，我们推测，血管扩张剂-NO与血浆低密度脂蛋白apoB-100的氨基酸成分的化学相互作用有助于浓缩和稍后释放-NO，从而减轻氧化的低密度脂蛋白在其他方面的促动脉粥样硬化作用。为了解决这些概念，将追求两个关键的实验目标。我们将1)测量NO扩散和分配到人血浆低密度脂蛋白的速率，以及2)识别-NO与apo B-100氨基酸自由基的加合物，并确定这些新物种的抗氧化和信号作用。这些拟议的研究将为理解-NO对低密度脂蛋白氧化和随后的动脉粥样硬化事件的启动、传播和分解的深刻影响的潜在机制提供坚实的基础。因此，该研究计划将探索-NO与脂蛋白的新的化学相互作用，从而对-NO依赖的抗动脉粥样硬化过程产生新的见解。

The experimental goals described in this new FIRCA application address fundamental mechanisms underlying the principal source of morbidity and mortality in Westernized countries, atherosclerosis. They also serve as the foundation for further expanding the mutually beneficial collaborative research and training activities in free radical biology and medicine shared by investigators at the University of Alabama at Birmingham School of Medicine and the Facultad de Medicina of the Universidad de la Repdblica in Montevideo, Uruguay. Specifically, the theme of the parent grant, that -NO mediates antioxidant actions in membrane lipids and lipoproteins, will be expanded in a new and important direction by addressing the novel concept that -NO can exert these effects by interacting with protein- based radicals. It is hypothesized that -NO plays a critical role in modulating LDL oxidation by: a) a facile diffusion capacity into both the surface and the core of the LDL particle, thus representing the major antioxidant species in the lipophilic core of LDL, and b) diffusion- controlled reactions with apoB-100-centered amino acid radicals, thus inhibiting both lipid and protein oxidation reactions. In addition, we postulate that chemical interactions of the vasodilator -NO with amino acid components of plasma LDL apoB-100 serve to concentrate and later release -NO, thus mitigating the otherwise pro-atherogenic effects of oxidized LDL. To address these concepts, two key experimental aims will be pursued. We will 1) Measure rates of -NO diffusion and partitioning into human plasma LDL and 2) Identify -NO adducts with apo B-100 amino acid radicals and define the antioxidant and signaling roles of these novel species. These proposed investigations will provide a strong foundation for understanding mechanisms underlying the profound impact that -NO has on the initiation, propagation and resolution of both LDL oxidation and consequent atherogenic events. Thus, the research plan will explore novel chemical interactions of -NO with lipoproteins, yielding new insight into -NO-dependent anti- atherogenic processes.