Skeletal muscle ion and volume regulation at rest, during contraction and recovery

我的研究继续研究调节骨骼肌和完好哺乳动物体内离子和液体平衡的机制。长期目标是增加对影响骨骼肌功能和全身表现的过程的基本知识和理解，在活动和恢复活动中。短期目标是：1)继续研究骨骼肌钠-钾-氯转运体(NKCC)的功能和调节；2)开始研究收缩活动恢复后骨骼肌细胞Na，K泵活性的调节机制；3)研究大强度运动对收缩期间和恢复期间肌肉钾转运途径的影响。我们以一种综合的方式使用了两种主要的实验方法，从分子到组织层面。第一种方法使用完整的、分离的大鼠后肢准备，注入已知和恒定成分的人造血液。这种方法的优势在于，它允许确定血管和肌肉间的净和单向离子、代谢物和液体流量，以及测量大鼠后肢分层纤维型群体内的离子和代谢物变化。这些条件与体内发现的条件非常接近，但也赋予了增加灌流液成分控制和实验范例的好处。第二种方法使用体外研究的小鼠骨骼肌束或单纤维来确定细胞内离子状态、膜电位和细胞体积在响应高渗应激、离子转运激活剂和离子转运抑制剂时的变化过程。这项工作有望加深我们对骨骼肌和整个动物在休息、运动、疲劳和恢复过程中离子和液体调节的理解。进一步预计，结果将转移到涉及电解质、收缩和代谢失衡的肌肉病理研究，如肌肉营养不良和II型糖尿病。

My research continues to examine mechanisms of regulating ion and fluid balance in skeletal muscle and in intact mammals. The long-term objectives are to increase the basic knowledge and understanding of the processes affecting skeletal muscle function and whole body performance during activity and recovery from activity. The short-term objectives are to: 1) continue to study the function and regulation of the skeletal muscle sodium-potassium-chloride cotransporter (NKCC); 2) to begin to study mechanisms of regulating Na,K pump activity in skeletal muscle cells recovering from contractile activity; and 3) examine the influence of high intensity exercise on muscle potassium transport pathways during both the contractile period and during recovery. We use two main experimental approaches in an integrated manner that spans from molecular to the tissue level. The first approach uses an intact isolated rat hindlimb preparation that is perfused with an artificial blood of known and constant composition. The strength of this approach is that it permits the determination of net and unidirectional ion, metabolite and fluid fluxes between vascular and muscle compartments, together with measurements of ion and metabolite changes within the stratified fiber type population of the lower rat hindlimb. The conditions closely approximate those found in vivo, yet confer the benefits of increased control of perfusate composition and the experimental paradigm. The second approach uses mouse skeletal muscle bundles or single fibres studied in vitro to determine the time course of change in intracellular ion status, membrane potential and cell volume in response hypertonic stress, ion transport activators and ion transport inhibitors. This work is expected to improve our understanding of skeletal muscle and whole animal ion and fluid regulation during rest, exercise, fatigue and recovery. It is further expected that the results will transfer to the study of muscle pathologies involving electrolyte, contractile and metabolic imbalances such as muscular dystrophy and type II diabetes.