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

越来越多的证据表明， NO有效浓度与动脉粥样硬化加速 糖尿病和其他疾病。尽管如此， 异常及其发生的机制是 不完全理解。在最近的研究中，我们观察到， 高血糖抑制NO合成，如通过精氨酸测定的 在培养的猪主动脉内皮中转化为瓜氨酸， 尽管它同时增强精氨酸的摄取。 在本建议中，我们将尝试定义 精氨酸转运和NO合成的改变 高血糖症及其机制。在 此外，我们将研究精氨酸转运和NO合成 在体内，在对照组和四氧嘧啶糖尿病组的主动脉中， 喂食致动脉粥样硬化饮食的兔子。具体目标如下： (1)为了确定高血糖对NO生成的影响， 培养的内皮细胞。精氨酸通过Na+转运 依赖性和Na非依赖性转运蛋白将被表征 我们将研究这两个系统与NO的关系 合成.然后我们将评估具体影响， 高血糖对这些过程的影响。研究的含义 我们还将针对这些活动进行蜂窝NOS分发 使用人胚肾细胞的类似研究 用myrostolation缺陷型和野生型eNOS转染。（二） 为了确定细胞信号传导和代谢的变化， 高血糖症，并检查它们的关系，其影响 L-Arg/NO通路。氧化还原状态、NADPH、DAG-PKC的变化 信号传导和Na泵活性将在时间上与 精氨酸转运和NO合成的改变。此外，本发明还提供了一种方法， 如果有必要，我们将检查抑制剂的作用， 或模拟L-Argl/NO途径上的这些变化。在这些 研究中，我们将比较慢性（天）与 急性高血糖症，并与项目1合作， 修饰的LDL对这些事件的影响。(3)为了确定L-Arg/NO 完整主动脉中的通路受糖尿病影响， 动脉粥样硬化 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。另外在 与项目3相配合，我们将绘制 主动脉中的通路，并评估它们是否与 糖尿病患者动脉粥样硬化发生的区域倾向 用米勒-威尔逊饮食喂养兔子。我们还将确定 L-Arg/NO通路的变化早于 这些兔子的动脉粥样硬化病变，以及它们是否 通过干预措施防止或逆转， 动脉粥样硬化。这些研究提供了基本的 关于精氨酸转运和NO调节的信息 主动脉内皮细胞中的合成以及它们是如何改变的 高血糖症为了配合项目3的努力， 也应该提供新的见解的作用，L-ArgI/NO 动脉粥样硬化的途径，以及糖尿病对其的加速作用。

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.