Mechanical ventilation, oxidative stress, and diaphragmatic atrophy

机械通气、氧化应激和膈肌萎缩

• 批准号: 7808778
• 负责人: Scott K. Powers
• 金额: $ 36.25万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7808778
• 关键词: Address; Alveolar; Animal Model; Animals; Antioxidants; Atrophic; Bed rest; Calpain; Cell Culture Techniques; Cells; Clinical; Data; Disease; Environmental air flow; Excision; Failure; Figs - dietary; Functional disorder; Goals; Health Care Costs; Immobilization; Individual; Intervention; Life; Link; Mechanical ventilation; Methods; Microfilaments; Modeling; Modification; Morbidity - disease rate; Muscle Fibers; Muscle Weakness; Myofibrils; Outcome; Oxidative Stress; Patients; Peptide Hydrolases; Peptide Mapping; Peptides; Play; Predisposition; Prevention; Proteins; Pulmonary Gas Exchange; Rattus; Research; Respiratory Diaphragm; Respiratory Failure; Respiratory Muscles; Risk; Role; Signal Transduction; Skeletal Muscle; Small Interfering RNA; Technology; Testing; Theoretical model; Weaning; Withdrawal; Work; base; calpastatin; caspase-3; innovation; knock-down; mortality; novel; oxidation; prevent; public health relevance; research study; skeletal muscle wasting

DESCRIPTION (provided by applicant): Mechanical ventilation (MV) is used clinically as a life saving intervention to sustain adequate pulmonary gas exchange in patients that are incapable of maintaining sufficient alveolar ventilation (e.g., patients in respiratory failure). The removal of patients from MV is termed "weaning" and problems in weaning are extremely common. The inability to wean patients from MV results in increased risk of morbidity and mortality along with higher health care costs. Studies indicate that MV-induced diaphragmatic weakness, due to both atrophy and contractile dysfunction, is a significant contributor to weaning difficulties. Our research reveals that prolonged MV is associated with diaphragmatic oxidative stress and that the activation of two proteases, calpains and caspase-3, is required for MV-induced diaphragmatic atrophy and contractile dysfunction. The mechanism(s) that regulate the activity of these proteases in the diaphragm during prolonged MV are currently unknown and will be addressed in this application. HYPOTHESES: Aim 1 will test the hypothesis that oxidative stress is essential for activation of both calpain and caspase-3 in the diaphragm during prolonged MV. Aim 2 will test the postulate that oxidative modification of diaphragmatic myofilament proteins increases their susceptibility to degradation by calpains-1/2 and/or caspase-3. Aim 3 will test the hypothesis that regulatory cross-talk between calpain and caspase-3 plays a vital role in determining the individual activity of these proteases. APPROACH: We will test these hypotheses using a combination of experimental paradigms including an animal model of MV, peptide mapping, and cell-signaling experiments performed in rat primary skeletal muscle cell culture. Cause and effect will be determined by prevention of MV-induced oxidative stress in the diaphragm and by the independent inhibition of calpains and caspase-3 in primary skeletal muscle myotubes using innovative approaches. SIGNIFICANCE AND LONG-TERM GOAL: Failure to wean patients from MV is an important clinical problem and respiratory muscle weakness is a major contributor to weaning difficulties. Hence, our long-term goal is to develop methods for the prevention of MV-induced diaphragmatic weakness based on an understanding of the cellular mechanisms responsible for MV-induced atrophy in the diaphragm. Moreover, the results of these experiments should provide important information for broader topics such as skeletal muscle wasting due to prolonged bed rest, immobilization, and disease states. PUBLIC HEALTH RELEVANCE: Mechanical ventilation (MV) is used to sustain pulmonary gas exchange in patients that are incapable of maintaining adequate alveolar ventilation; the withdrawal of MV from patients is referred to as "weaning" and problems in weaning from MV are extremely common. Numerous studies reveal that MV-induced diaphragmatic weakness, due to both atrophy and contractile dysfunction, is an important contributor to weaning difficulties. Our long-term goal is to develop methods for the prevention of MV-induced diaphragmatic weakness based on an understanding of the cellular mechanisms responsible for MV-induced diaphragmatic atrophy and contractile dysfunction.

描述（由申请人提供）：机械通气（MV）在临床上用作挽救生命的干预措施，以维持无法维持足够肺泡通气的患者的适当肺气交换（例如，呼吸衰竭患者）。从MV中取出患者被称为“断奶”，断奶问题非常普遍。无法从MV中解脱患者导致发病率和死亡率的风险增加，以及更高的医疗保健成本。研究表明，由于萎缩和收缩功能障碍，MV诱导的diaphragmmantation无力是断奶困难的重要原因。我们的研究表明，长时间的MV与diaphragmagmantagragmantagation抗氧化应激有关，并且MV诱导的diaphragragmaragmatic萎缩和收缩功能障碍需要两种蛋白酶（CALPAINS和CASPASE-3）的激活。目前尚不清楚调节这些蛋白酶在隔膜中这些蛋白酶活性的机制，并将在本应用中解决。假设：AIM 1将检验以下假设：氧化应激对于延长MV期间diaphragm中钙蛋白酶和caspase-3的激活至关重要。 AIM 2将测试假设diaphragmantic肌丝蛋白的氧化修饰会增加其对CalPains-1/2和/或caspase-3的降解的敏感性。 AIM 3将检验以下假设：钙蛋白酶和caspase-3之间的调节性串扰在确定这些蛋白酶的个体活性中起着至关重要的作用。方法：我们将使用实验范式的组合来检验这些假设，包括MV动物模型，肽映射和在大鼠原发性骨骼肌细胞培养中进行的细胞信号实验。因素和作用将通过预防膜片中MV诱导的氧化应激以及使用创新方法在原代骨骼肌肌肉管中独立抑制CALPAINS和CASPASE-3的独立抑制来确定。意义和长期目标：不从MV中解除患者是一个重要的临床问题，呼吸道肌肉无力是断奶困难的主要原因。因此，我们的长期目标是基于对负责MV诱导的膜片萎缩的细胞机制的理解，开发预防MV诱导的diaphragmmantic弱点的方法。此外，这些实验的结果应为更广泛的主题提供重要信息，例如由于长时间的休息，固定和疾病状态而引起的骨骼肌浪费。公共卫生相关性：机械通气（MV）用于维持无法维持足够肺泡通气的患者的肺气交换；从患者中撤出MV被称为“断奶”，从MV断奶中的问题非常普遍。大量研究表明，由于萎缩和收缩功能障碍，MV诱导的diaphragmmantagic无力是造成断奶困难的重要原因。我们的长期目标是基于对负责MV诱导的diaphragmmapmatic萎缩和收缩功能障碍的细胞机制的理解，开发预防MV诱导的diaphragmmantic弱点的方法。