Nutritional and Contractile Regulation of Muscle Growth

描述（由申请人提供）：该项目的重点是研究调节人类骨骼肌生长的生理机制。肌肉萎缩是许多疾病中的常见现象，例如癌症、艾滋病、创伤、败血症、肾衰竭，并且在老年人中也特别普遍。肌肉质量的损失导致整体虚弱，不动和身体依赖，并可能导致对压力的反应受损，这与感染，手术和创伤期间的死亡率较高有关。 营养和抗阻运动是骨骼肌蛋白质合成的两大刺激因素。我们的一般假设是，蛋白质合成代谢反应的大小将由这两种刺激之间的相互作用决定。特别是，我们提出，骨骼肌蛋白质的增长是依赖于营养刺激的时间与运动回合和营养刺激提供的能量的量。我们进一步假设，营养刺激或肌肉收缩后的肌肉蛋白合成代谢反应在健康的年轻男性中比在年轻女性中更明显。 具体目标：（1）测定骨骼肌蛋白质合成和净蛋白质合成对一次抗阻运动前后给予的营养刺激的急性反应的幅度。(2)确定骨骼肌蛋白质合成和净蛋白质摄入对营养刺激的急性反应的幅度，所述营养刺激提供的能量与运动诱导的能量消耗相匹配或超过运动诱导的能量消耗。(3)为了确定女性和男性之间的骨骼肌蛋白质合成的反应，蛋白质合成的氨基酸利用效率，亮氨酸氧化，和净蛋白质的抗阻运动单独和结合营养刺激之前或之后的阻力运动。 意义这些研究将提供对调节人体肌肉蛋白质平衡的生理机制的深入了解，并将作为开发基于科学的干预措施的基础，以改善衰老，创伤，癌症和艾滋病等条件下的肌肉蛋白质平衡。

DESCRIPTION (provided by applicant): The focus of this project is to examine physiological mechanisms that regulate human skeletal muscle growth. Muscle wasting is a common phenomenon in many conditions, such as cancer, AIDS, trauma, sepsis, kidney failure, and is also particularly prevalent in the elderly. The loss of muscle mass leads to overall weakness, immobility and physical dependence, and can be responsible for an impaired response to stress, which is associated with higher mortality rates during infection, surgery, and trauma. Nutrition and resistance exercise are two major protein anabolic stimuli for skeletal muscle. Our general hypothesis is that the magnitude of the protein anabolic response will be determined by the reciprocal interactions between these two stimuli. In particular, we propose that skeletal muscle protein accretion is dependent upon both the timing of the nutritional stimulus in relation to the exercise bout and the amount of energy provided by the nutritional stimulus. We further hypothesize that the muscle protein anabolic response following a nutrient stimulus or muscular contraction will be more pronounced in healthy young men than in young women. Specific aims: (1) To determine the magnitude of the acute response of skeletal muscle protein synthesis and net protein anabolism to a nutritional stimulus given before or after a bout of resistance exercise. (2) To determine the magnitude of the acute response of skeletal muscle protein synthesis and net protein anabolism to a nutritional stimulus providing an amount of energy that either matches or exceeds the exercise-induced energy expenditure. (3) To determine the differences between women and men in the response of skeletal muscle protein synthesis, efficiency of amino acid utilization for protein synthesis, leucine oxidation, and net protein anabolism to resistance exercise alone and in combination with a nutritional stimulus delivered before or after a bout of resistance exercise. Significance. These studies will provide insight into physiological mechanisms that regulate human muscle protein balance, and will be utilized as a basis from which to develop scientificallybased interventions for improving muscle protein balance in conditions such as aging, trauma, cancer, and AIDS.