Centre for Heart Lung Innovation, St. Paul's Hospital, Providence Health Care, University of British Columbia, 1081 Burrard Street, Vancouver, BC, V6Z 1Y6, Canada.
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
Respir Res. 2023 Oct 18;24(1):250. doi: 10.1186/s12931-023-02538-8.
Deep inspiration (DI) has been shown to induce bronchodilation and bronchoprotection in bronchochallenged healthy subjects, but not in asthmatics. Strain-induced relaxation of airway smooth muscle (ASM) is considered one of the factors responsible for these effects. Other factors include the release or redistribution of pulmonary surfactant, alteration in mucus plugs, and changes in airway heterogeneity.
The present review is focused on the DI effect on ASM function, based on recent findings from ex vivo sheep lung experiments showing a large change in airway diameter during a DI. The amount of stretch on the airways, when applied to isolated airway rings in vitro, caused a substantial decrease in ASM contractility that takes many minutes to recover. When challenged with a bronchoconstrictor, the increase in pulmonary resistance in the ex vivo ovine lungs is mostly due to the increase in airway resistance.
Although non-ASM related factors cannot be excluded, the large strain on the airways associated with a DI substantially reduces ASM contractility and thus can account for most of the bronchodilatory and bronchoprotective effects of DI.
深吸气（DI）已被证明可诱导支气管挑战健康受试者的支气管扩张和支气管保护作用，但对哮喘患者则无此作用。气道平滑肌（ASM）的应变松弛被认为是这些作用的原因之一。其他因素包括肺表面活性物质的释放或重分布、黏液栓的改变以及气道异质性的变化。
本综述重点介绍 DI 对 ASM 功能的影响，这是基于最近从离体绵羊肺实验中得出的发现，该实验显示在 DI 过程中气道直径发生了很大变化。在体外分离的气道环上施加气道伸展量会导致 ASM 收缩性显著下降，需要数分钟才能恢复。在离体绵羊肺中，当受到支气管收缩剂挑战时，肺阻力的增加主要是由于气道阻力的增加。
尽管不能排除非 ASM 相关因素，但与 DI 相关的大应变会大大降低 ASM 的收缩性，因此可以解释 DI 的大部分支气管扩张和支气管保护作用。
