Hyperinflation of bronchi in vitro impairs bronchodilation to simulated breathing and increases sensitivity to contractile activation

Respirology : Official Journal of the Asian Pacific Society of Respirology
Alvenia CairncrossP K McFawn

Abstract

Lung hyperinflation and reduced bronchodilation to deep inspiration (DI) are features of chronic obstructive pulmonary disease (COPD). Hyperinflation might impair the ability of a DI to stretch airway smooth muscle (ASM), as the bronchi operate at a stiff region of the pressure-volume curve. Bronchial segments from pig lungs were mounted in an organ bath and equilibrated at either 5 cm H2 O (control) or 20 cm H2 O (hyperinflated) transmural pressure (Ptm ). Cumulative dose-response curves to acetylcholine (ACh) were performed to determine maximal response (Emax ) and sensitivity under static conditions (fixed Ptm ) or during simulated breathing (Δ10 cm H2 O Ptm at 0.25 Hz). The effect of hyperinflation on ASM contraction was further examined in bronchial rings contracted at a short ASM length (reference length, Lref ) or stretched by an additional 30% (length 1.3 times the Lref , 1.3Lref ). Oscillatory loads halved Emax from 61.0 ± 3.8 to 29.7 ± 4.4 cm H2 O (P < 0.0001) in control bronchial segments, but only from 40.0 ± 2.5 to 31.2 ± 2.4 cm H2 O (P < 0.05) in hyperinflated segments. The percentage reduction in active pressure with oscillation was less in hyperinflated compared with control segments (P < 0.01). Sensitivity was ...Continue Reading

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Citations

Mar 7, 2018·Respirology : Official Journal of the Asian Pacific Society of Respirology·Jason H T Bates
Aug 18, 2020·Journal of Developmental Origins of Health and Disease·Kevin LooiKimberley C W Wang
Feb 1, 2019·Journal of Engineering and Science in Medical Diagnostics and Therapy·Ynuk Bossé
Sep 12, 2019·Frontiers in Physiology·Peter B NobleKimberley C W Wang
Apr 5, 2019·Respirology : Official Journal of the Asian Pacific Society of Respirology·John W Upham

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