Redox Mechanisms of Respiratory Muscle Stress Adaptation

骨骼肌在应对各种应激刺激时产生活性氧簇(ROS)，包括 热应激、渗透应激、强烈刺激和低氧。这些信号似乎在功能上 很重要，但在大多数正常生理条件下不会造成伤害或损害。我们假设 在这种情况下，ROS在信号网络中扮演重要角色，旨在帮助细胞抵御 压力。目前提案的重点将放在从高氧气向低氧气过渡过程中产生的ROS 在骨骼肌中。这一现象与缺氧引起的细胞氧化还原状态的改变是一致的。 细胞(NADH/NAD+)，但我们不知道信号是来自氧化还原的变化还是其他一些低氧- 诱导的细胞反应。我们也不知道这种信号的亚细胞来源或什么表型。 生产它。提案的目标1将确定ROS形成的主要细胞和亚细胞来源 在新陈代谢应激期间产生，它将决定ROS生成系统对 PO2的变化与NADH/NAD+的变化。为了达到这个目的，我们设计了新的成像方法， 包括多光子寿命和荧光寿命，以及一种用于定位超氧化物的新型荧光探针 接近细胞膜。我们还将通过测量确定关键的刺激形式和强度，以及 独立操控PO2和电池氧化还原状态。在AIM 2中，我们将研究其功能意义 低氧诱导的ROS。我们假设应激诱导的ROS促进能量动员并抑制 能源支出。首先，我们将评估AMP依赖的蛋白激酶和糖酵解的潜在作用。 通量作为应激诱导ROS的可能靶标。其次，我们将确定ROS如何影响 钙离子释放与作用力的关系及ROS和细胞氧化还原状态的可能作用 改变钙离子诱导的作用力。这项基础科学研究将对基本骨骼提供新的见解 肌肉生物学将应用于与氧气运输受限相关的各种肌肉疾病。

Skeletal muscles produce reactive oxygen species (ROS) in response to a variety of stress stimuli, including thermal stress, osmotic stress, intense stimulation and hypoxia. These signals appear to be functionally significant but do not cause injury or damage under most normal physiologic conditions. We hypothesize that ROS, in this setting, play important roles in signaling networks designed to assist cells to withstand stress. The focus of the current proposal will be on the ROS produced in the transition from high to low O2 in skeletal muscle. This phenomenon is coincident with the hypoxia-induced shift in the redox state of the cell (NADH/NAD+), but we do not know if the signal arises from changes in redox or some other hypoxia- induced cellular response. We also do not know the sub-cellular origins of this signal or what phenotype produces it. AIM 1 of the proposal will identify the primary cellular and subcellular origins of ROS formation produced during metabolic stress and it will determine the sensitivity of the ROS-generating system to changes in PO2 vs. shifts in NADH/NAD+. To address this aim we have designed new imaging methods, including multiphoton and fluorescence lifetime, and a new fluorescent probe for localization of superoxide close to membranes. We will also determine the critical stimulus modality and intensity by measuring, and independently manipulating PO2 and cell redox state. In AIM 2, we will study the functional significance of hypoxia-induced ROS. We hypothesize that stress-induced ROS promotes energy mobilization and inhibits energy expenditure. First, we will evaluate the potential role of AMP-dependent protein kinase and glycolytic flux as a possible target for stress-induced ROS. Second, we will determine how ROS influences the relationships between Ca+2 release and force and the potential roles ROS and cell redox state have in altering Ca+2-induced force. This basic science investigation will give new insights into fundamental skeletal muscle biology that will have applications to a variety of muscle disorders related to O2 transport limitation.