Document Detail

Closing and opening pressures in the intrapulmonary airways of rats.
MedLine Citation:
PMID:  622514     Owner:  NLM     Status:  MEDLINE    
Pressures at which the peripheral airways (PA) and terminal bronchioles (TB), open and closed, were studied in rats' lungs in vitro. Airway luminal diameter was directly measured at diminishing transbronchial pressure (closing) and increasing transbronchial pressure (opening) by means of a stereomicroscope with a calibrated eyepiece. The PA and TB had internal diameters at 100 mm H2O ranging from 173 to 306 micrometer and 122 to 204 micrometer, respectively. Most of the airways closed suddenly in the pressure range between 75 and 5 mm H2O and only a few were still open at zero pressure. Closure began in the distal portion of the PA and mid-portion of the TB usually in a concentric manner. Terminal bronchioles and PA that initially were prepared at room temperature instead of at 0 degrees C often contained air at zero pressure and showed a decreased response to acetylcholine. Subthreshold concentrations of acetylcholine increased the critical closing pressure by more than 100%. The critical opening pressure was considerably higher than the corresponding closing pressure. It is proposed that bronchiolar closure depends on the tone of the airway smooth muscle, the elasticity of the airway wall and probably on the surface tension of the liquid lining the mucosal membrane.
G N Melville; J Iravani; H G Richter
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Respiration; international review of thoracic diseases     Volume:  35     ISSN:  0025-7931     ISO Abbreviation:  Respiration     Publication Date:  1978  
Date Detail:
Created Date:  1978-03-10     Completed Date:  1978-03-10     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0137356     Medline TA:  Respiration     Country:  SWITZERLAND    
Other Details:
Languages:  eng     Pagination:  22-9     Citation Subset:  IM    
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MeSH Terms
Acetylcholine / pharmacology
Bronchi / anatomy & histology,  physiology*
Reg. No./Substance:

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