Journal of Applied Physiology, Vol 73, Issue 4 1481-1485, Copyright © 1992 by American Physiological Society

ARTICLES

Mechanical properties of human bronchial smooth muscle in vitro

K. Ishida, P. D. Pare, J. Hards and R. R. Schellenberg
Pulmonary Research Laboratory, University of British Columbia, St. Paul's Hospital, Vancouver, Canada.

The in vitro mechanical properties of smooth muscle strips from 10 human main stem bronchi obtained immediately after pneumonectomy were evaluated. Maximal active isometric and isotonic responses were obtained at varying lengths by use of electrical field stimulation (EFS). At the length (Lmax) producing maximal force (Pmax), resting tension was very high (60.0 +/- 8.8% Pmax). Maximal fractional muscle shortening was 25.0 +/- 9.0% at a length of 75% Lmax, whereas less shortening occurred at Lmax (12.2 +/- 2.7%). The addition of increasing elastic loads produced an exponential decrease in the shortening and velocity of shortening but increased tension generation of muscle strips stimulated by EFS. Morphometric analysis revealed that muscle accounted for 8.7 +/- 1.5% of the total cross-sectional tissue area. Evaluation of two human tracheal smooth muscle preparations revealed mechanics similar to the bronchial preparations. Passive tension at Lmax was 10-fold greater and maximal active shortening was threefold less than that previously demonstrated for porcine trachealis by us of the same apparatus. We attribute the limited shortening of human bronchial and tracheal smooth muscle to the larger load presumably provided by a connective tissue parallel elastic component within the evaluated tissues, which must be overcome for shortening to occur. We suggest that a decrease in airway wall elastance could increase smooth muscle shortening, leading to excessive responses to contractile agonists, as seen in airway hyperresponsiveness.

This article has been cited by other articles:

				G.G. King, J.D. Carroll, N.L. Muller, K.P. Whittall, M. Gao, Y. Nakano, and P.D. Pare Heterogeneity of narrowing in normal and asthmatic airways measured by HRCT Eur. Respir. J., August 1, 2004; 24(2): 211 - 218. [Abstract] [Full Text] [PDF]

				B. Fabry, G. N. Maksym, S. A. Shore, P. E. Moore, R. A. Panettieri Jr., J. P. Butler, and J. J. Fredberg Signal Transduction in Smooth Muscle: Selected Contribution: Time course and heterogeneity of contractile responses in cultured human airway smooth muscle cells J Appl Physiol, August 1, 2001; 91(2): 986 - 994. [Abstract] [Full Text] [PDF]

				U. Holzhauser and R. K. Lambert Analysis of tracheal mechanics and applications J Appl Physiol, July 1, 2001; 91(1): 290 - 297. [Abstract] [Full Text] [PDF]

				A. M. OPAZO SAEZ, C. Y. SEOW, and P. D. PARE Peripheral Airway Smooth Muscle Mechanics in Obstructive Airways Disease Am. J. Respir. Crit. Care Med., March 1, 2000; 161(3): 910 - 917. [Abstract] [Full Text] [PDF]

				Am. J. Respir. Crit. Care Med., May 1, 1999; 159(5): 1684 - 1684. [Full Text]

				F.-X. Blanc, S. Salmeron, C. Coirault, M. Bard, E. Fadel, E. Dulmet, P. Dartevelle, and Y. Lecarpentier Effects of load and tone on the mechanics of isolated human bronchial smooth muscle J Appl Physiol, February 1, 1999; 86(2): 488 - 495. [Abstract] [Full Text] [PDF]

				R. A. Meiss Influence of intercellular tissue connections on airway muscle mechanics J Appl Physiol, January 1, 1999; 86(1): 5 - 15. [Abstract] [Full Text] [PDF]

				R. K. Lambert and P. D. Pare Lung parenchymal shear modulus, airway wall remodeling, and bronchial hyperresponsiveness J Appl Physiol, July 1, 1997; 83(1): 140 - 147. [Abstract] [Full Text] [PDF]