Oxidant Mediated Diaphragm Dysfunction in Diabetes

描述（由申请人提供）：最近的研究表明，糖尿病与呼吸衰竭的发生率增加、术后呼吸并发症的风险增加以及更需要长时间的机械通气相关。然而，尚不清楚糖尿病如何产生这些问题。一个可能的解释是，不受控制的糖尿病改变了呼吸肌功能，降低了呼吸泵的能力。本申请的目的是研究这个问题。我们的中心假设是，控制不佳的糖尿病诱导严重的自由基介导的膈肌功能障碍。我们将在以下几组研究中检验这一假设。目标1研究将描述未控制的糖尿病对膈肌比力产生、肌肉质量变化和膈肌耐力的影响，检验糖尿病诱导的膈肌性能改变与自由基产生增加相关的假设。目的2研究将询问肌肉中的许多自由基生成途径（包括细胞表面NADPH氧化酶），并确定哪些途径是糖尿病膈肌中自由基生成增加的原因。目的3研究将确定糖尿病患者膈肌中iNOS是否上调，并将检验iNOS作为自由基产生的上游调节剂的假设。目的4研究将检查糖尿病诱导的膈肌自由基生成的几个下游靶点，这些靶点导致膈肌性能降低，包括收缩蛋白改变、钙蛋白酶介导的肌肉质量减少和线粒体ATP生成能力改变。各种生理学、生物化学、蛋白质组学、荧光、药理学和遗传学技术将被用来检验这些假设。我们的初步数据代表了在任何疾病过程中骨骼肌中NADPH氧化酶亚基蛋白上调的第一个证明，并表明iNOS调节糖尿病中膈肌中NADPH氧化酶活性和自由基的产生。这些新的数据应该提供关于糖尿病引起的膈肌功能障碍的发病机制的重要信息，并揭示可以为治疗这种情况下的呼吸肌无力提供新的治疗靶点的途径。

DESCRIPTION (provided by applicant): Recent studies indicate that diabetes is associated with an increased incidence of respiratory failure, a heightened risk of postoperative respiratory complications, and a greater need for prolonged mechanical ventilation. Nevertheless, it is not known how diabetes produces these problems. One potential explanation is that uncontrolled diabetes alters respiratory muscle function, reducing the capacity of the respiratory pump. The purpose of the current application is to examine this issue. Our central hypothesis is that poorly controlled diabetes induces severe free radical mediated diaphragm dysfunction. We will test this hypothesis in the following groups of studies. Aim 1 studies will characterize the effects of uncontrolled diabetes on diaphragm specific force generation, changes in muscle mass, and diaphragm endurance, testing the hypothesis diabetes induced alterations in diaphragm performance are related to increases in free radical generation. Aim 2 studies will interrogate a number of free radical generating pathways in muscle (including the cell surface NADPH oxidase) and determine which pathways are responsible for increased free radical generation in the diaphragm in diabetes. Aim 3 studies will determine if iNOS is upregulated in the diaphragm in diabetes, and will test the hypothesis that iNOS acts as an upstream modulator of free radical generation. Aim 4 studies will examine several downstream targets of diabetes induced free radical generation in the diaphragm that are responsible for reductions in diaphragm performance, including contractile protein alterations, calpain mediated reductions in muscle mass, and alterations in mitochondrial ATP generating capacity. A variety of physiologic, biochemical, proteomic, fluorogenic, pharmacologic and genetic techniques will be used to test these hypotheses. Our preliminary data represent the first demonstration of upregulation of NADPH oxidase subunit proteins in skeletal muscle in any disease process, and suggest that iNOS regulates NADPH oxidase activity and free radical generation in the diaphragm in diabetes. These new data should provide important information regarding the pathogenesis of diabetes induced diaphragm dysfunction, and uncover pathways which could provide novel therapeutic targets for treatment of respiratory muscle weakness in this condition.