In situ measurement of sarcomere operating range in passive and active muscle

被动和主动肌肉肌节工作范围的原位测量

• 批准号: 8384368
• 负责人: Matthew Tresch
• 金额: $ 17.38万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8384368
• 关键词: Address; Articular Range of Motion; Behavior; Development; Exercise; Generations; Goals; Health; Hindlimb; Image; In Situ; Individual; Injury; Joints; Knowledge; Length; Life; Limb structure; Locomotion; Measurement; Measures; Methods; Microscopy; Movement; Muscle; Muscle Development; Muscle Fibers; Muscle function; Myopathy; Pattern; Preparation; Process; Property; Rattus; Research; Research Personnel; Resort; Sarcomeres; Spatial Distribution; Spectrum Analysis; Stretching; Techniques; Testing; Tissues; Variant; experience; in vivo; innovation; insight; neuroregulation; research study; tissue fixing; two-photon

DESCRIPTION (provided by applicant): Sarcomere lengths are one of the main determinants of how a muscle contributes to behavior. Whether a muscle functions primarily for movement stabilization or for power generation is strongly influenced by the sarcomere lengths over which that muscle operates. Moreover, alterations in sarcomere properties contribute to muscle damage following injury. Although investigators have used a variety of methods to measure sarcomere lengths, the ability to measure these lengths in situ and how they vary when the limb is moved or when the muscle is active, remains a fundamental challenge. The research in this proposal will develop a promising new technique, two photon microscopy, to measure sarcomere lengths in muscles in situ. This technique will allow us to characterize sarcomere length variations across muscles, limb configurations, and activation patterns. Importantly, it also will allow us to begin characterizing how these measures change following exercise related muscle damage. This technique has several potential advantages over current techniques of characterizing sarcomere lengths of muscles. First, it can measure sarcomere lengths without disturbing muscle fibers, so sarcomere lengths can be measured in an intact muscle. Second, sarcomere lengths can be measured in functioning muscles, so that effects of activation can be directly evaluated. Such measurements are impossible with current techniques of measuring sarcomere lengths. Third, multiple sarcomere length measurements can be made quickly and repeatedly, so that we can examine sarcomere operating ranges directly without resorting to extrapolation. This repeatability also allows us to visualize the development of muscle damage during exercise related activity in situ; e.g. tracking sarcomere properties in the same muscle as damage is progressively induced through eccentric contractions. Finally, we will perform these measurements in an in vivo preparation that we have recently developed for measuring muscle actions, so that we will be able to measure both sarcomere lengths and muscle actions in situ. The ability to collect these measurements together in the same preparation will give us unprecedented insight into the function of a muscle and how it contributes to behavior. We have three specific aims in this proposal. First, we will measure the operating range of sarcomeres across a large number of muscles in the rat hindlimb, to determine the relationship between sarcomere lengths and hypothesized muscle functions. Second, we will measure the change in sarcomere operating ranges after muscle activation, to determine the degree to which neural control alters sarcomere operating ranges. Finally, we will image sarcomeres during the development of muscle damage induced by eccentric contractions. If successful, this research has the potential to directly address these fundamental issues of muscle function and disease, demonstrating the potential power of two photon microscopy in studies of muscle function. PUBLIC HEALTH RELEVANCE: The experiments described in this proposal will develop an innovative technique for making in situ measurements of sarcomeres in muscles. The force produced by a muscle is critically determined by these sarcomere lengths and yet these lengths can be difficult to measure in living tissue. We will use two photon microscopy to measure these sarcomere lengths in living muscle, characterizing directly how these micro scale muscle properties contribute to macro scale aspects of muscle function. We will also examine sarcomere properties during the induction of muscle damage from exercise related activity, providing new insights into the structural substrate underlying injury.

描述（由申请人提供）：肌节长度是肌肉如何影响行为的主要决定因素之一。肌肉的功能主要是稳定运动还是产生能量，这在很大程度上取决于肌肉运行时肌节的长度。此外，肌节特性的改变有助于损伤后的肌肉损伤。尽管研究人员已经使用了多种方法来测量肌节长度，但原位测量这些长度以及当肢体运动或肌肉活动时它们如何变化的能力仍然是一个根本性的挑战。本提案的研究将发展一种有前途的新技术，双光子显微镜，测量肌肉的肌节长度在原位。这项技术将使我们能够描述肌肉的肌节长度变化、肢体结构和激活模式。重要的是，它还将允许我们开始描述这些指标在运动相关肌肉损伤后是如何变化的。与目前表征肌肉肌节长度的技术相比，该技术有几个潜在的优势。首先，它可以在不干扰肌纤维的情况下测量肌节长度，因此可以在完整的肌肉中测量肌节长度。其次，可以在功能肌肉中测量肌节长度，从而可以直接评估激活的效果。用目前测量肌节长度的技术是不可能进行这样的测量的。第三，可以快速、重复地测量多个肌节的长度，这样我们就可以直接检查肌节的活动范围，而不需要外推。这种可重复性也使我们能够在运动相关活动中实地观察肌肉损伤的发展；例如，当损伤通过偏心收缩逐渐引起时，追踪同一块肌肉的肌节特性。最后，我们将在我们最近开发的用于测量肌肉活动的体内制剂中进行这些测量，这样我们就能够测量肌节长度和原位肌肉活动。在相同的准备中收集这些测量数据的能力将使我们对肌肉的功能及其对行为的影响有前所未有的了解。我们在这项建议中有三个具体目标。首先，我们将测量大鼠后肢大量肌肉中肌节的活动范围，以确定肌节长度与假设的肌肉功能之间的关系。其次，我们将测量肌肉激活后肌节活动范围的变化，以确定神经控制改变肌节活动范围的程度。最后，我们将在偏心收缩引起的肌肉损伤发展过程中对肌节进行成像。如果成功，这项研究有可能直接解决肌肉功能和疾病的这些基本问题，展示了双光子显微镜在肌肉功能研究中的潜在力量。