MR DIAGNOSIS OF MUSCLE METABOLISM AND FUNCTION

长期目标是开发人类肌肉的诊断程序 功能使用以前用于评估的既定策略 动物肌肉的新陈代谢和收缩特性。 在这 我们使用成像和光谱学来定义能量的基础 在正常肢体肌肉中的范例。 首先，我们开发并验证一个新的 运动应激试验，以测量氧化和收缩能力， 人类四肢肌肉 其次，我们用这些能力来评估肌肉 在正常运动过程中获得的能量平衡的基础上的功能。 定量能量压力测试：该测试使用神经刺激 在缺血肌肉中测定ATP酶（收缩）能力， 磷酸肌酸分解（dPCr/dt）。 术后PCr恢复率 局部缺血定义了ATP合成（氧化）能力（Specific Aims 1和2）。 这些能力结合在一起产生定量信息 用于评估肌肉的肌纤维类型分类之外 功能能力。 能量平衡：为了验证该策略的预测能力，我们 确定在稳态神经网络下达到的能量平衡， 刺激和自然锻炼。 我们测试是否有更高的氧化 1）在相同的运动水平下， （2）更大的持续力量生产和锻炼水平。 这项工作 建立在广泛的光谱信息的基础上， 正常和患病的人体肌肉，并根据生物能量学原理， 来自动物研究的代谢整合。 新的是， 能量平衡概念首次应用于人体肌肉， 新陈代谢经济的供需双方 可以定量评估并与肌肉功能能力相关。

The long-term goal is to develop diagnostic procedures for human muscle function using well established strategies previously used for evaluating the metabolic and contractile properties of animal muscle. In this project we use imaging and spectroscopy to define the basis energetic paradigm in normal limb muscle. First, we develop and validate a new exercise stress test to measure oxidative and contractile capacity of human limb muscle. Second, we use these capacities to assess muscle function based on the energy balance attained during normal exercise. Quantitative Energetic Stress Test: This test uses neural stimulation in ischemic muscle to determine ATPase (contractile) capacity as the rate of creatine phosphate breakdown (dPCr/dt). The PCr recovery rate after ischemia defines the ATP synthesis (oxidative) capacity (Specific Aims 1 and 2). Together these capacities yield quantitative information beyond muscle fiber-type classification for assessment of muscle functional capacity. Energy Balance: To validate the predictive power of the strategy, we determine the energy balance attained under steady-state neural stimulation and natural exercise. We test whether a higher oxidative capacity results in 1) less depletion of PCr at the same exercise level and 2) greater sustained force production and exercise levels. This work builds on an extensive body of spectroscopic information gained from normal and diseased human muscle, and on principles of bioenergetics and metabolic integration derived from animal studies. What is new is the energy balance concept is applied for the first time to human muscle in a way in which both the supply and demand side of the metabolic economy can be quantitatively assessed and related to muscle functional capacity.