Can breathing-like pressure oscillations reverse or prevent narrowing of small intact airways?
Can breathing-like pressure oscillations reverse or prevent narrowing of small intact airways?
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类似呼吸的压力波动能否逆转或防止完整的小气道变窄？
DOI：
10.1152/japplphysiol.01100.2014
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Lutchen,KennethR
中科院分区：
文献类型：
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作者：
Harvey,BrianC;Parameswaran,Harikrishnan;Lutchen,KennethR
呼吸过程中气道平滑肌长度的周期性波动被认为可以调节气道的体内反应。最近对动物和人类完整气道的研究表明，模拟呼吸的压力波动只能略微逆转气道狭窄，对防止未来气道狭窄无效。然而，这些先前的研究是在相对较大的气道（直径0.5 mm）上进行的，这些气道固有地比较小的气道更硬，而较小的气道在哮喘中更容易发生气道收缩。本研究的目的是确定呼吸样跨壁压力振荡对逆转诱导狭窄和/或防止未来更小、更柔顺的完整气道狭窄的有效性。我们用ACh （10 - 6M）两次收缩较小（管径= 2.92±0.29 mm）的完整气道段，一次是在诱导收缩之前、期间和之后（前+后）施加潮汐样压力振荡（5-15 cmH2O），另一次是在诱导收缩后仅施加潮汐样压力振荡（仅后）。较小的气道比先前研究的较大的气道顺应性高128%。由于类似潮汐的压力振荡，这种顺应性的增加意味着应变增加了196%，恢复提高了76%（41%对23%）。较大的压力振荡（5-25 cmH2O）可提高采收率（77.5±16.5%）。然而，收缩前和收缩期间施加压力振荡与收缩后施加压力振荡所产生的稳态直径相同。这些数据表明，在挑战之前减少气道紧张可能不会导致哮喘中观察到的气道高反应性的出现，但可能有助于维持给定的收缩水平。
Periodic length fluctuations of airway smooth muscle during breathing are thought to modulate airway responsiveness in vivo. Recent animal and human intact airway studies have shown that pressure fluctuations simulating breathing can only marginally reverse airway narrowing and are ineffective at protecting against future narrowing. However, these previous studies were performed on relatively large (>5 mm diameter) airways, which are inherently stiffer than smaller airways for which a preponderance of airway constriction in asthma likely occurs. The goal of this study was to determine the effectiveness of breathing-like transmural pressure oscillations to reverse induced narrowing and/or protect against future narrowing of smaller, more compliant intact airways. We constricted smaller (luminal diameter = 2.92 ± 0.29 mm) intact airway segments twice with ACh (10−6M), once while applying tidal-like pressure oscillations (5–15 cmH2O) before, during, and after inducing constriction (Pre + Post) and again while only imposing the tidal-like pressure oscillation after induced constriction (Post Only). Smaller airways were 128% more compliant than previously studied larger airways. This increased compliance translated into 196% more strain and 76% greater recovery (41 vs. 23%) because of tidal-like pressure oscillations. Larger pressure oscillations (5–25 cmH2O) caused more recovery (77.5 ± 16.5%). However, pressure oscillations applied before and during constriction resulted in the same steady-state diameter as when pressure oscillations were only applied after constriction. These data show that reduced straining of the airways before a challenge likely does not contribute to the emergence of airway hyperreactivity observed in asthma but may serve to sustain a given level of constriction.