Scaling of the Mechanics and Energetics of Mammalian Muscle Fibers with Body Size

经验表明，小动物（如小鼠和大鼠）比大动物（人或马）移动四肢的频率更高，而且每克小动物移动一定距离所消耗的能量比大动物多。在这个提案中，首席研究员（PI）将提出这样的问题：“肌肉系统是如何设计的，以允许小动物更快的运动，为什么小动物比大动物跑步消耗更多的能量？”据推测，这种差异在于肌肉纤维的特性。小动物的肌肉纤维被认为要快得多——这是这些动物以高频率奔跑的必要条件。但这是有代价的：非常快的肌肉纤维要消耗更多的能量来产生力量，因此可能解释了为什么小动物跑起来更昂贵。PI将通过测量从老鼠到马等动物产生不同纤维类型的力的速度和能量消耗与体型的比例来验证上述假设。PI研究的长期目标是了解肌肉系统的设计。这包括进行特定的实验，以促进来自分子、细胞和整个动物研究的信息整合。这种方法是至关重要的，因为我们对动物使用肌肉的原理的了解还有很大的空白。此外，阐明健康运动系统如何工作的原则可能在人类和其他动物的健康和运动表现方面具有深远的应用。例如，从这些研究中获得的信息可能有助于1)了解运动/心血管系统的疾病/损伤；2)设计辅助残疾人运动的计算机系统；3)针对肌肉疾病状态设计药物和基因干预；4)了解训练/康复的功能基础；5)选择合适的骨骼肌进行心脏泵送辅助。由于最近尝试将非人类物种的组织用于人体，这些研究将特别重要，因为它们将提供肌肉速度的数据库，医生可以从中选择适合人类特定功能的良好匹配。这一信息对兽医也很重要。＊＊＊

9514383 Rome It has been empirically shown that small animals (e.g. mice and rats) move their limbs at higher frequencies than large animals (man or horses) and that it costs more energy per gram for a small animal to move a given distance than for a large one. In this proposal, the principal investigator (PI) will ask "how is the muscular system designed to permit much faster movements in small animals and why does it cost much more energy for small animals to run than large ones?" It has been hypothesized that the difference lies in the properties of the muscle fibers. The muscle fibers of the small animals are thought to be much faster--a necessity for the high frequencies at which these animals run. But there is a price: very fast muscle fibers use far more energy to generate force, thus potentially explaining why it is more costly for small animals to run. The PI will test the above hypothesis by measuring how speed and the energetic cost of generating force of different fiber types scales with body size in animals ranging from rats to horses. The long-term goal of the PI's research is to understand the design of muscular systems. This involves performing specific experiments that facilitate the integration of information from molecular, cellular and whole animal studies. This approach is crucial because there are large gaps in our knowledge of the principles by which animals use their muscles. Further, elucidation of the principles of how healthy motor systems work may have far-reaching application in terms of health and athletic performance of humans and other animals. For instance, the information obtained from these studies may be useful in 1) understanding disease/injuries of the motor/cardiovascular systems; 2) designing computer systems for aiding movement in the handicapped; 3) designing pharmacological and genetic interventions for muscle disease states; 4) understanding the functional basis of training/rehabilitation; and 5) choosing appropriate skeletal muscle fo r heart pumping assist. With recent attempts to use tissue from non-human species in man, these studies would be particularly important as they will provide a data base of muscle speeds from which physicians might be able to choose a good match for a particular function in humans. This information will also be important for veterinary medicine. ***