|
|
||||||||
Department of Physiology, University of Western Australia, Perth, Western Australia 6009, Australia
Increased smooth muscle contractility or reduced smooth muscle mechanical loads could account for the excessive airway narrowing and hyperresponsiveness seen in asthma. These mechanisms were investigated by using an allergen-induced porcine model of airway hyperresponsiveness. Airway narrowing to electric field stimulation was measured in isolated bronchial segments, over a range of transmural pressures (0-20 cmH2O). Contractile responses to ACh were measured in bronchial segments and in isolated tracheal smooth muscle strips isolated from control and test (ovalbumin sensitized and challenged) pigs. Test airways narrowed less than controls (P < 0.0001). Test pigs showed reduced contractility to ACh, both in isolated bronchi (P < 0.01) and smooth muscle strips (P < 0.01). Thus isolated airways from pigs exhibiting airway hyperresponsiveness in vivo are hyporesponsive in vitro. The decreased narrowing in bronchi from hyperresponsive pigs may be related to decreased smooth muscle contractility. These data suggest that mechanisms external to the airway wall may be important to the hyperresponsive nature of sensitized lungs.
bronchial hyperreactivity; respiratory mechanics; bronchoconstriction
This article has been cited by other articles:
![]() |
Y. Bai and M. J. Sanderson The contribution of Ca2+ signaling and Ca2+ sensitivity to the regulation of airway smooth muscle contraction is different in rats and mice Am J Physiol Lung Cell Mol Physiol, June 1, 2009; 296(6): L947 - L958. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Park, C. Stafford, and W. Lockette Exercise-Induced Asthma May Be Associated With Diminished Sweat Secretion Rates in Humans Chest, September 1, 2008; 134(3): 552 - 558. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. B. Noble, A. Sharma, P. K. McFawn, and H. W. Mitchell Airway narrowing in porcine bronchi with and without lung parenchyma Eur. Respir. J., November 1, 2005; 26(5): 804 - 811. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |