Document Detail

High lung volume increases stress failure in pulmonary capillaries.
MedLine Citation:
PMID:  1506359     Owner:  NLM     Status:  MEDLINE    
We previously showed that when pulmonary capillaries in anesthetized rabbits are exposed to a transmural pressure (Ptm) of approximately 40 mmHg, stress failure of the walls occurs with disruption of the capillary endothelium, alveolar epithelium, or sometimes all layers. The present study was designed to test whether stress failure occurred more frequently at high than at low lung volumes for the same Ptm. Lungs of anesthetized rabbits were inflated to a transpulmonary pressure of 20 cmH2O, perfused with autologous blood at 32.5 or 2.5 cmH2O Ptm, and fixed by intravascular perfusion. Samples were examined by both transmission and scanning electron microscopy. The results were compared with those of a previous study in which the lung was inflated to a transpulmonary pressure of 5 cmH2O. There was a large increase in the frequency of stress failure of the capillary walls at the higher lung volume. For example, at 32.5 cmH2O Ptm, the number of endothelial breaks per millimeter cell lining was 7.1 +/- 2.2 at the high lung volume compared with 0.7 +/- 0.4 at the low lung volume. The corresponding values for epithelium were 8.5 +/- 1.6 and 0.9 +/- 0.6. Both differences were significant (P less than 0.05). At 52.5 cmH2O Ptm, the results for endothelium were 20.7 +/- 7.6 (high volume) and 7.1 +/- 2.1 (low volume), and the corresponding results for epithelium were 32.8 +/- 11.9 and 11.4 +/- 3.7. At 32.5 cmH2O Ptm, the thickness of the blood-gas barrier was greater at the higher lung volume, consistent with the development of more interstitial edema. Ballooning of the epithelium caused by accumulation of edema fluid between the epithelial cell and its basement membrane was seen at 32.5 and 52.5 cmH2O Ptm. At high lung volume, the breaks tended to be narrower and fewer were oriented perpendicular to the axis of the pulmonary capillaries than at low lung volumes. Transmission and scanning electron microscopy measurements agreed well. Our findings provide a physiological mechanism for other studies showing increased capillary permeability at high states of lung inflation.
Z Fu; M L Costello; K Tsukimoto; R Prediletto; A R Elliott; O Mathieu-Costello; J B West
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  73     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1992 Jul 
Date Detail:
Created Date:  1992-09-21     Completed Date:  1992-09-21     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  123-33     Citation Subset:  IM; S    
Department of Medicine, University of California, San Diego, La Jolla 92093-0623.
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MeSH Terms
Air Pressure
Barotrauma / physiopathology
Blood-Air Barrier
Capillaries / physiopathology
Endothelium / physiology
Epithelium / physiology
Lung / physiopathology*
Microscopy, Electron
Microscopy, Electron, Scanning
Pulmonary Circulation / physiology*
Stress, Physiological / physiopathology*
Tissue Fixation
Total Lung Capacity / physiology
Grant Support
J B West / U CA, San Diego

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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