MECHANISMS OF LIPID A TOXICITY IN RENAL PROXIMAL TUBULES

描述：(改编自《调查者摘要》)急性肾功能衰竭 是严重细菌感染的常见后果，通常是致命的。 人类。研究人员之前的研究表明，激活脑组织 一氧化氮合酶(NOS)负责细胞毒 细菌内毒素(脂多糖)对肾脏近端的影响 小管。脂类A是脂多糖的生物活性部分，起作用 通过释放细胞内钙离子，进而激活一氧化氮合酶，产生一氧化氮 一代。虽然在几分钟内没有检测到世代，但细胞死亡 发生在2+年后很多。然而，细胞毒性可以通过(A)预防。 抑制钙离子释放，(B)一氧化氮合酶抑制剂，或(C)抗氧化剂。这个 拟议的研究将解决这一假设，即一氧化氮合酶的早期激活 和随后的氧化应激是脂类A的主要决定因素 毒性。在具体目标1和2中，调查人员将审查 由脂质A和一氧化氮触发的生化事件最终导致 细胞毒性。在具体目标3中，他们将研究一氧化氮合酶的作用 内毒素性急性胰腺炎模型的激活和氧化剂生成 肾功能衰竭。要实现上述所有目标，具体目标如下 建议；1)他们将研究钙离子在激活细胞周期中的作用。 近端小管一氧化氮合酶采用两种不同的方法。第一个是 用部分纯化的制剂进行酶学鉴定。这个 第二种方法是利用脂类A刺激完整的离体小管。 2.)调查人员将研究NO世代在人类进化中的作用 脂质A的细胞毒性指数将评估一氧化氮合酶的有效性 抑制剂、NO清除剂和氧化剂清除剂，以及钙离子释放 对亚致死发展到致死损伤的抑制作用。3.)《少年派》 将在体内研究NO在内毒素诱导的肾功能衰竭中的作用。 利用内毒素诱导的肾功能衰竭模型，他们将研究这种作用 A型脂蛋白和内毒素诱导的急性肾损伤中一氧化氮和氧化剂的变化 在与体外培养过程相似的时间进程中发展的失败 学习。对一氧化氮合酶活性调控的认识 没有世代的后果对于理解人类的作用至关重要 近曲小管一氧化氮的病理生理及新疗法的开发 来治疗人类疾病。

DESCRIPTION: (Adapted from the Investigator's Abstract) Acute renal failure is a frequent and often fatal consequence of severe bacterial infection in humans. The investigators's previous studies indicate that activation of the enzyme nitric oxide synthase (NOS) is responsible for the cytotoxic effects of bacterial endotoxin (lipopolysaccharide) in the kidney proximal tubule. Lipid A, the biologically active moiety of lipopolysaccharide, acts by releasing intracellular Ca2+ which in turn activates NOS resulting in NO generation. Although NO generation is detected within minutes, cell death occurs much 2+ later. Nevertheless, cytotoxicity can be prevented by (a) inhibiting Ca2+ release, (b) inhibitors of NOS, or (c) antioxidants. The proposed studies will address the hypothesis that early activation of NOS and subsequent oxidant stress are the major determinants of lipid A toxicity. In specific aims 1 and 2, the investigators will examine the biochemical events triggered by lipid A and NO that ultimately lead to cytotoxicity. In specific aim 3 they will examine the role of NOS activation and oxidant generation in a model of endotoxin-induced acute renal failure. To accomplish all of the above, the following specific aims are proposed; 1.) they will examine the role of Ca2+ in the activation of proximal tubule NOS using two complimentary approaches. The first is enzymatic characterization using a partially purified preparation. The second approach utilizes intact isolated tubules stimulated with lipid A. 2.) the investigators will examine the role of NO generation in the cytotoxicity of lipid A. The PI will evaluate the effectiveness of NOS inhibitors, NO scavengers and oxidant scavengers, and Ca 2+ release inhibitors on the development of sublethal to lethal injury. 3.) The PI will examine the role of NO in endotoxin-induced renal failure in vivo. Using a model of endotoxin-induced renal failure, they will examine the role of NO and oxidants in lipid A and lipopolysaccharide-induced acute renal failure that develop over a similar time course as in their in vitro studies. An understanding of the regulation of NOS activity and the consequence of NO generation is crucial to the understanding of the role of NO in proximal tubule pathophysiology and the development of new therapies to treat the human disease.