Capturing the in situ behavior of airway smooth muscle in human bronchi using an ex vivo system that simulates breathing maneuvers

使用模拟呼吸动作的离体系统捕获人支气管中气道平滑肌的原位行为

• 批准号: RGPIN-2014-04395
• 负责人: Bossé, Ynuk
• 金额: $ 2.26万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=611008
• 关键词: Capturing; situ; behavior; airway; smooth

The physiologic function of airway smooth muscle (ASM) within the lung is unknown. The lack of ascribed function of such an elaborated structure, which is present in every airway from the trachea to the respiratory bronchioles, perplexes a lot of investigators. We believe that this puzzlement arises from the methods and techniques that are traditionally used to study ASM contraction. An improved ex vivo setting that simulates more accurately the in vivo conditions in which ASM operates may be required to capture its in situ behavior and to decipher its role in the mechanics of breathing. The force deployed by ASM relies on a balance between a myriad of both spasmogen (e.g. acetylcholine) and bronchodilators (e.g. nitric oxide), which collectively determine the level of ASM activation. However, the force deployed by ASM is not only a function of its level of activation. The length at which ASM operates also significantly affects its capacity to generate force. To gain valuable insights into the physiologic function of ASM in vivo, it is thus imperative to study ASM at in situ length. We recently described how ASM can be studied at in situ length ex vivo (within an organ bath). We demonstrated that the in situ length of ASM is surprisingly far from the optimal length (i.e. the length at which maximal force occurs). However, these experiments were performed in static conditions. Although our findings represented significant advance to the understanding of ASM biology, our ex vivo setting can be improved to emulate in vivo conditions even more closely. The length at which ASM is called to operate in vivo is not static. The lung is a dynamic organ that requires substantial and continuous changes of volume to fulfill its ventilatory function. These changes of volume impose oscillatory changes in the length of ASM. Thus, in addition of being set at in situ length, ASM needs to be studied during changes of length that simulate the changes of lung volume that occur in vivo. The goal of this program is to determine the role of ASM in the mechanics of human bronchi within an ex vivo setting that recreates the dynamic environment in which ASM operates in vivo. This research program aims to: 1-Determine the length-force relationship of ASM in human bronchi at different levels of ASM activation during dynamic and repetitive cycles of lengthening and shortening within a range of lengths that ASM can experience in vivo. 2-Determine whether the rate of length change, within a range of rates that can occur in vivo, affects ASM length-force relationship. 3-Determine whether the choice of spasmogen used to activate ASM influences the response. 4-Fit these experimental data into a computational model to estimate the influence of changing ASM activation and length on ASM shortening, airway narrowing and resistance to airflow in individual airways of different sizes. This project will determine the amount of force generated by ASM of human bronchi at different levels of activation during physiological range and rate of length changes. It will also predict how length and ASM activation combine to affect ASM shortening, airway narrowing and resistance to airflow. Ultimately, it will determine how all these factors interact to affect lung function. We believe that a better characterization of the length-force relationship of ASM in a dynamic system that simulates the perpetual changes of lung volume that occur in vivo is a prerequisite to understand the physiologic function of ASM. This program will provide highly qualified personnel (HQP) with cutting edge expertise in respiratory physiology, biomechanics, tissue biology, pharmacology and computational modeling analyses.

肺内气道平滑肌（ASM）的生理功能尚不清楚。从气管到呼吸性细支气管的每一个气道都存在这样一个复杂的结构，但它缺乏应有的功能，这使许多研究人员感到困惑。我们认为，这种困惑源于传统上用于研究ASM收缩的方法和技术。可能需要更准确地模拟ASM操作的体内条件的改进的离体设置，以捕获其原位行为并破译其在呼吸力学中的作用。 由ASM展开的力依赖于无数的致痉挛剂（例如乙酰胆碱）和支气管扩张剂（例如一氧化氮）之间的平衡，其共同决定ASM激活的水平。然而，ASM部署的部队不仅仅是其激活程度的函数。个体和小规模军事行动的时间长短也严重影响到其组建部队的能力。为了获得有价值的见解ASM在体内的生理功能，因此，必须研究ASM在原位长度。 我们最近描述了如何在体外原位长度（在器官浴内）研究ASM。我们证明了ASM的原位长度与最佳长度（即发生最大力时的长度）相差甚远。然而，这些实验在静态条件下进行。虽然我们的发现代表了对ASM生物学理解的重大进展，但我们的离体设置可以改进以更接近地模拟体内条件。 ASM被调用在体内操作的长度不是静态的。肺是一个动态器官，需要大量和连续的体积变化来实现其呼吸功能。这些体积的变化使ASM的长度产生振荡变化。因此，除了被设置在原位长度之外，还需要在模拟体内发生的肺体积变化的长度变化期间研究ASM。该计划的目标是确定ASM在体外环境中的人体支气管力学中的作用，该体外环境重建了ASM在体内运行的动态环境。 该研究计划旨在： 1-在ASM体内可能经历的长度范围内，在动态和重复的延长和缩短周期期间，在不同水平的ASM激活下，确定人体支气管中ASM的长度-力关系。 2-确定在体内可能发生的速率范围内的长度变化速率是否影响ASM长度-力关系。 3-确定用于激活ASM的痉挛原的选择是否影响反应。 4-将这些实验数据拟合到计算模型中，以估计改变ASM激活和长度对不同尺寸的个体气道中的ASM缩短、气道狭窄和气流阻力的影响。 该项目将确定在生理范围和长度变化率期间，在不同激活水平下，人体支气管ASM产生的力的大小。它还将预测长度和ASM激活如何结合联合收割机来影响ASM缩短、气道狭窄和气流阻力。最终，它将确定所有这些因素如何相互作用以影响肺功能。我们认为，一个更好的表征ASM的长度-力的关系，在一个动态的系统，模拟在体内发生的肺体积的永久变化是一个先决条件，以了解ASM的生理功能。该计划将提供在呼吸生理学，生物力学，组织生物学，药理学和计算建模分析方面具有尖端专业知识的高素质人员（HQP）。