Detection of two clusters of mechanical properties of smooth muscle
along the airway tree.
Ma, Xuefei, Weilong Li, and Newman L. Stephens.
Department of Physiology, Faculty of Medicine, University of
Manitoba, 770 Bannatyne Ave., Winnipeg, Manitoba, R3E 0W3, Canada
APStracts 2:0458A, 1995.
Heterogeneity of function of airway smooth muscle along the airways
may be of great importance in regulating regional ventilation and in
the pathogenesis of asthma. To investigate the distribution of
mechanical properties of airway smooth muscle along the airway,
muscle strips free of cartilage and epithelium from the trachea down
to bronchial generation 6 were studied employing electric field
stimulation. Results showed that smooth muscle mechanical performance
decreased progressively down the airway tree. Cluster analysis
further indicated that smooth muscle from these airways could be
divided into two groups: 1. An extrapulmonary group, containing
muscle from the trachea, and bronchial generations 1 and 2,
characterized by higher _Lmax, and Vo in early shortening, and the
expected decrease of Vo's (the so-called latch phase) in the later
phase of shortening, and lower sensitivity to stimulation, 2. An
intrapulmonary group, containing bronchi from generation 3 to 6, with
lower _Lmax and Vo in early shortening but higher sensitivity to
stimulation. The relatively lower mechanical performance of
intrapulmonary bronchial smooth muscle may represent a safety device
preventing excessive smooth muscle shortening in vivo.
Received 13 February 1995; accepted in final form 9 October 1995.
APS Manuscript Number A161-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95