Document Detail

Airway smooth muscle orientation in intraparenchymal airways.
MedLine Citation:
PMID:  9029200     Owner:  NLM     Status:  MEDLINE    
Airway smooth muscle (ASM) shortening is the central event leading to bronchoconstriction. The degree to which airway narrowing occurs as a consequence of shortening is a function of both the mechanical properties of the airway wall as well as the orientation of the muscle fibers. Although the latter is theoretically important, it has not been systematically measured to date. The purpose of this study was to determine the angle of orientation of ASM (theta) in normal lungs by using a morphometric approach. We analyzed the airway tree of the left lower lobes of four cats and one human. All material was fixed with 10% buffered Formalin at a pressure of 25 cmH2O for 48 h. The fixed material was dissected along the airway tree to permit isolation of generations 4-18 in the cats and generations 5-22 in the human specimen. Each airway generation was individually embedded in paraffin. Five-micrometer-thick serial sections were cut parallel to the airway long axis and stained with hematoxylin-phloxine-saffron. Each block yielded three to five sections containing ASM. To determine theta, we measured the orientation of ASM nuclei relative to the transverse axis of the airway by using a digitizing tablet and a light microscope (x250) equipped with a drawing tube attachment. Inspection of the sections revealed extensive ASM crisscrossing without a homogeneous orientation. The theta was clustered between -20 degrees and 20 degrees in all airway generations and did not vary much between generations in any of the cats or in the human specimen. When theta was expressed without regard to sign, the mean values were 13.2 degrees in the cats and 13.1 degrees in the human. This magnitude of obliquity is not likely to result in physiologically important changes in airway length during bronchoconstriction.
M Lei; H Ghezzo; M F Chen; D H Eidelman
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  82     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1997 Jan 
Date Detail:
Created Date:  1997-04-28     Completed Date:  1997-04-28     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:  70-7     Citation Subset:  IM    
Meakins-Christie Laboratories, Montreal Chest Institute Research Centre, Royal Victoria General Hospital, McGill University, Quebec, Canada.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Lung / anatomy & histology*
Muscle, Smooth / anatomy & histology*
Respiratory Muscles / anatomy & histology*

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

Previous Document:  Muscle capillarization O2 diffusion distance, and VO2 kinetics in old and young individuals.
Next Document:  Effects of a synthetic lung surfactant on pharyngeal patency in awake human subjects.