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Excessive airway obstruction is the cause of symptoms and abnormal lung function in asthma. As airway smooth muscle (ASM) is the effecter controlling airway calibre, it is suspected that dysfunction of ASM contributes to the pathophysiology of asthma. However, the precise role of ASM in the series of events leading to asthmatic symptoms is not clear. It is(More)
In this study, isovolumic bronchial segments and bronchial rings were used to investigate the influence of airway diameter on smooth muscle force generation and acetylcholine responsiveness. Segments with internal diameters ranging from 1.0-6.0 mm were obtained from the mainstem bronchus of eight pigs. Responses to increasing acetylcholine concentrations(More)
During bronchoconstriction elastic after-loads arise due to distortion of lung parenchyma by the narrowing airway. In the present study, the functional effect of parenchymal elastic after-load on airway narrowing was determined. Airway narrowing was measured in vivo over a range of transpulmonary pressures and compared with in vitro narrowing measured at(More)
In healthy individuals, deep inspiration produces bronchodilation and reduced airway responsiveness, which may be a response of the airway wall to mechanical stretch. The aim of this study was to examine the in vitro response of isolated human airways to the dynamic mechanical stretch associated with normal breathing. Human bronchial segments (n = 6) were(More)
Model studies incorporating known morphological properties of the airways predict different narrowing characteristics between large and small bronchi. However, the flow-response characteristics of airways from different regions in the bronchial tree are still unknown. We compared the responsiveness of large and small bore bronchi of the pig to luminal or(More)
Maturational changes in the specific compliance could potentially contribute to the development or clinical presentation of respiratory diseases in infants and children. Changes in the specific compliance during development and its structural basis have been well characterized, but changes in bronchial compliance and the mechanisms involved have received(More)
In vivo, breathing movements, including tidal and deep inspirations (DIs), exert a number of beneficial effects on respiratory system responsiveness in healthy humans that are diminished or lost in asthma, possibly as a result of reduced distension (strain) of airway smooth muscle (ASM). We used bronchial segments from pigs to assess airway responsiveness(More)
DYNAMIC RESPIRATORY MOVEMENTS such as deep inspiration (DI) are believed to play an important role in limiting airway narrowing, and a failure of this physiological regulation is offered as a potential pathway to airway hyperresponsive-ness in asthma (1). While our understanding of the mecha-nism(s) involved is incomplete, beneficial effects of DI are(More)
Bronchoconstrictor responses are quantitatively different when they are evoked under static conditions and during or after periods of deep inspiration. In vivo, deep inspirations produce bronchodilation and protect the lung from subsequent bronchoconstriction (termed bronchoprotection). These effects may be due in part to dynamic stretch on airways produced(More)
The amount of smooth muscle shortening required to cause narrowing of the bronchial lumen and to significantly alter airflow in an airway has not not been measured. Accordingly, in this study, the lumens of isolated fluid-filled bronchial segments from pigs were directly visualized using a fibreoptic endoscope and video-recording. The extent of lumen(More)