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对长时间机械通气的需求增加有关。然而，目前尚不清楚糖尿病是如何产生这些问题的。一种可能的解释是，不受控制的糖尿病改变了呼吸肌功能，降低了呼吸泵的容量。当前应用程序的目的是检查这个问题。我们的中心假设是控制不佳的糖尿病诱导了严重的自由基介导的隔膜功能障碍。我们将在以下几组研究中检验这一假设。目的1研究将描述不受控制的糖尿病对横膈膜比力产生、肌肉质量变化和横膈膜耐力的影响，验证糖尿病引起的横膈膜性能改变与自由基生成增加有关的假设。目的2研究将询问肌肉中自由基生成的一些途径（包括细胞表面NADPH氧化酶），并确定哪些途径是导致糖尿病膈肌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，并将验证iNOS作为自由基生成上游调节剂的假设。Aim 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标，这些靶标负责膈肌性能的降低，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生成能力的改变。各种生理学、生物化学、蛋白质组学、荧光学、药理学和遗传学技术将被用来检验这些假设。我们的初步数据首次证明了在任何疾病过程中骨骼肌中NADPH氧化酶亚基蛋白的上调，并表明iNOS调节糖尿病膈肌中NADPH氧化酶的活性和自由基的产生。这些新数据将为糖尿病引起膈肌功能障碍的发病机制提供重要信息，并为该病呼吸肌无力的治疗提供新的治疗靶点。

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.