DIABETES, HYPERGLYCEMIA AND THE L-ARGININE/NITRIC OXIDE PATHWAY

越来越多的证据表明， 一氧化氮有效浓度与动脉粥样硬化的关系 糖尿病和其他疾病。尽管如此，这些问题的本质 异常现象及其发生的机制是 不完全理解。在最近的研究中，我们观察到 根据精氨酸测定，高血糖抑制NO的合成 在培养的猪主动脉内皮细胞中转化为瓜氨酸， 尽管它同时增强了精氨酸的摄取。 在这项提案中，我们将尝试定义具体的 大鼠精氨酸转运和一氧化氮合成的改变 高血糖及其致病机制。在……里面 此外，我们还将研究精氨酸的转运和NO的合成 在体内，在对照组和四氧嘧啶糖尿病患者的主动脉中发生改变 给兔子喂食致动脉粥样硬化的食物。具体目标如下： (1)观察高血糖对大鼠脑内NO生成的影响。 培养内皮细胞。精氨酸在钠离子中的转运 依赖和钠非依赖的转运蛋白将被表征 我们将研究这两个系统与NO之间的关系 综合。然后我们将评估以下各项的具体影响 高血糖对这些过程的影响。要考察以下方面的影响 关于细胞一氧化氮合酶分布的这些事件，我们还将进行 稳定使用人胚胎肾细胞的类比研究 野生型内皮型一氧化氮合酶野生型和肉豆蔻醇缺陷型。(2) 为了定义细胞信号和新陈代谢的变化， 高血糖及其与其影响的关系 L-Arg/NO通路。氧化还原状态、NADPH、DAG-PKC的变化 信号转导和钠泵活动将在时间上与 精氨酸转运和一氧化氮合成的改变。此外, 如果有必要，我们将检查抑制药物的效果 或在L-Arg1/NO通路上模拟这些变化。作为这些计划的一部分 研究，我们将比较慢性(天数)和 急性高血糖，并与 修饰的低密度脂蛋白，对这些事件。(3)确定L如何-arg/no 在完整的主动脉中的通路受到糖尿病和 动脉硬化。我们将确定高血糖是否会导致 在培养的内皮细胞中也会发生同样的变化。此外，在 与项目3协调一致，我们将绘制出 并评估它们是否与 糖尿病患者发生动脉粥样硬化的区域倾向 兔子以米勒-威尔逊饮食喂养。我们还将确定是否 L-精氨酸/一氧化氮通路的变化早于血管紧张素转换酶 这些兔的动脉粥样硬化病变以及它们是否 通过减轻严重性的干预措施来防止或逆转 动脉粥样硬化的症状。这些研究应该提供基本的 精氨酸转运和一氧化氮调节的信息 主动脉内皮细胞的合成及其如何改变 由高血糖引起。在项目3的努力下，他们 也应该为L的角色提供新的见解-Argi/no 动脉粥样硬化的途径，以及糖尿病对其加速作用。

An increasing body of evidence has linked abnormalities in the effective concentration of NO with accelerated atherosclerosis in diabetes and other diseases. Despite this, the nature of these abnormalities and the mechanisms by which they occur are incompletely understood. In recent studies, we have observed that hyperglycemia inhibits NO synthesis, as measured by arginine conversion to citrulline, in cultured porcine aortic endothelium, despite the fact it concurrently enhances the uptake of arginine. In this proposal, we will attempt to define the specific alterations in arginine transport and NO synthesis caused by hyperglycemia and the mechanisms responsible for them. In addition, we will examine how arginine transport and NO synthesis are altered, in vivo, in the aorta of control and alloxan-diabetic rabbits fed an atherogenic diet. The specific aims are as follows: (1) To determine the effect of hyperglycemia on NO generation in cultured endothelial cells. Arginine transport through Na+ dependent and Na-independent transporters will be characterized and we 'will examine the relation of the two systems to NO synthesis. We will then assess the specific effects of hyperglycemia on these processes. To examine the implications of cellular NOS distribution on these events, we will also carry out analogous studies using human embryonic kidney cells stably transfected with myrostolation-deficient and wild type eNOS. (2) To define the changes in cell signalling and metabolism caused by hyperglycemia and to examine their relationship to its effects on the L-Arg/NO pathway. Changes in redox state, NADPH, DAG-PKC signalling, and Na pump activity will be related temporally to alterations in arginine transport and NO synthesis. In addition, if warranted, we will examine the effects of agents that inhibit or mimic these changes on the L-Argl/NO pathway. As part of these studies, we will compare the effects of chronic (days) versus acute hyperglycemia, and in collaboration with Project 1 of modified LDL, on these events. (3) To determine how the L-Arg/NO pathway in the intact aorta is affected by diabetes and atherosclerosis. We will determine whether hyperglycemia causes the same changes it does in cultured endothelium. In addition, in concert with project 3, we will map regional differences in the pathway in the aorta and assess whether they correlate with the propensity of a region to develop atherosclerosis in diabetic rabbits fed a Miller-Wilson diet. We will also determine whether changes in the L-Arg/NO pathway antedate the appearance of atherosclerotic lesions in these rabbits and whether they are prevented or reversed by interventions that diminish the severity of the atherosclerosis. These studies should provide basic information about the regulation of arginine transport and NO synthesis in the aortic endothelial cell and how they are altered by hyperglycemia. In concert with the efforts of project 3, they should also provide novel insights into the role of the L-ArgI/NO pathway in atherosclerosis, and its acceleration by diabetes.