Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University , Providence, Rhode Island.
J Appl Physiol (1985). 2019 Apr 1;126(4):823-831. doi: 10.1152/japplphysiol.01008.2018. Epub 2019 Jan 17.
We tested the hypothesis that oscillatory airway smooth muscle (ASM) mechanics is governed by mechanosensitive energy loss and energy release elements that can be recruited by prestrain and cholinergic stimulation. We measured mechanical energy loss and mechanical energy release in unstimulated and carbachol-stimulated bovine ASM held at prestrains ranging from 0.3 to 1.0 L (reference length) and subjected to sinusoidal length oscillation at 1 hz with oscillatory strain amplitudes ranging from 0.1 to 1.5% L. We found that oscillatory ASM mechanics during sinusoidal length oscillation is governed predominantly by one class of nonlinear mechanosensitive energy loss element and one class of nonlinear mechanosensitive energy release element with differential mechanosensitivities to oscillatory strain amplitude. The greater mechanosensitivity of the energy loss element than energy release element may explain the bronchodilatory effect of deep inspiration. Prestrain, an important determinant of ASM responsiveness, differentially increased energy loss and energy release in unstimulated and carbachol-stimulated ASM. Cholinergic stimulation, an important cause of bronchoconstriction and airway inflammation, also differentially increased energy loss and energy release. When prestrain and cholinergic stimulation were combined, we found that prestrain and cholinergic stimulation synergistically increased energy loss and energy release by ASM. The relationship between recruitment of energy loss elements and recruitment of energy release elements was nonlinear, suggesting that energy loss and energy release elements are not coupled in ASM cells. These findings imply that large lung volume and cholinergic ASM activation would synergistically increase mechanical energy expenditure during inspiration and mechanical recoil of ASM during expiration. NEW & NOTEWORTHY We report for the first time that oscillatory airway smooth muscle mechanics is governed predominantly by one class of nonlinear mechanosensitive energy loss element and one class of nonlinear mechanosensitive energy release element with differential mechanosensitivities to oscillatory strain amplitude. Prestrain and cholinergic stimulation synergistically and differentially recruit energy loss and energy release elements. The greater mechanosensitivity of the energy loss element than the energy release element may explain the bronchodilatory effect of deep inspiration.
我们测试了这样一个假设,即振荡气道平滑肌(ASM)力学由机械敏感的能量损失和能量释放元件控制,这些元件可以通过预应变和胆碱能刺激来募集。我们测量了在预应变范围为 0.3 至 1.0 L(参考长度)的未刺激和卡巴胆碱刺激的牛 ASM 中的机械能量损失和机械能量释放,并在 1 hz 下进行正弦长度振荡,振荡应变幅度范围为 0.1 至 1.5% L。我们发现,在正弦长度振荡期间,振荡 ASM 力学主要由一类非线性机械敏感能量损失元件和一类非线性机械敏感能量释放元件控制,它们对振荡应变幅度具有不同的机械敏感性。能量损失元件比能量释放元件的机械敏感性更大,这可能解释了深呼吸的支气管扩张作用。预应变是 ASM 反应性的一个重要决定因素,它对未刺激和卡巴胆碱刺激的 ASM 中均会不同程度地增加能量损失和能量释放。胆碱能刺激是支气管收缩和气道炎症的重要原因,它也不同程度地增加了能量损失和能量释放。当预应变和胆碱能刺激相结合时,我们发现预应变和胆碱能刺激通过 ASM 协同增加了能量损失和能量释放。能量损失元件和能量释放元件的募集之间的关系是非线性的,这表明在 ASM 细胞中,能量损失和能量释放元件没有耦合。这些发现意味着大的肺容量和胆碱能 ASM 激活将在吸气期间协同增加机械能量消耗,并在呼气期间协同增加 ASM 的机械回弹。新的和值得注意的是,我们首次报道,振荡气道平滑肌力学主要由一类非线性机械敏感能量损失元件和一类非线性机械敏感能量释放元件控制,这些元件对振荡应变幅度具有不同的机械敏感性。预应变和胆碱能刺激协同地和不同地募集能量损失和能量释放元件。能量损失元件的机械敏感性比能量释放元件大,这可能解释了深呼吸的支气管扩张作用。
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