Journal of Applied Physiology, Vol 79, Issue 1 348-356, Copyright © 1995 by American Physiological Society

ARTICLES

Dynamic viscoelastic nonlinearity of lung parenchymal tissue

D. Navajas, G. N. Maksym and J. H. Bates
Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada.

To investigate the contribution of nonlinear tissue viscoelasticity to the dynamic behavior of lung, time and frequency responses of isolated parenchymal strips of degassed dog lungs were investigated. The strips were subjected to loading and unloading stretch steps for 60 s and to sinusoidal oscillations (0.03-3 Hz) of different stretch amplitudes (delta lambda = 0.05, 0.1, and 0.2) and at different operating stresses (T(o) = 0.5, 1, and 2 kPa). Elastance (E) increased linearly with the logarithm of frequency (approximately 10% per frequency decade), and resistance (R) decreased hyperbolically with frequency. Both E and R varied little with delta lambda but they increased proportionally with T(o). Hysteresivity (eta = R x 2 pi x frequency/E) ranged from 0.07 to 0.10. In agreement with the frequency response, the magnitude of the unit step response increased with T(o) and was higher when loading than when unloading, and the stress relaxation ratio (approximately 0.10) did not vary greatly with T(o) or with delta lambda. The time and frequency behavior of the strips were interpreted in terms of the quasilinear viscoelastic model of Navajas et al. (J. Appl. Physiol. 73:2681-2692, 1992). The model explains most of the dependencies of step and oscillatory responses on the measurement conditions, in particular the proportional dependence of E and R on T(o). According to the model, about two-thirds of energy dissipated during oscillation arises from tissue viscoelasticity. The remaining dissipated energy could be accounted for by plasticity. Thus the effect of nonlinear elasticity on the dynamic behavior of lung tissue can be empirically described by a simple quasilinear model characterized by only two parameters.

This article has been cited by other articles:

				B. Suki, S. Ito, D. Stamenovic, K. R. Lutchen, and E. P. Ingenito Biomechanics of the lung parenchyma: critical roles of collagen and mechanical forces J Appl Physiol, May 1, 2005; 98(5): 1892 - 1899. [Abstract] [Full Text] [PDF]

				S. Ito, E. P. Ingenito, K. K. Brewer, L. D. Black, H. Parameswaran, K. R. Lutchen, and B. Suki Mechanics, nonlinearity, and failure strength of lung tissue in a mouse model of emphysema: possible role of collagen remodeling J Appl Physiol, February 1, 2005; 98(2): 503 - 511. [Abstract] [Full Text] [PDF]

				A. Fust, F. LeBellego, R. V. Iozzo, P. J. Roughley, and M. S. Ludwig Alterations in lung mechanics in decorin-deficient mice Am J Physiol Lung Cell Mol Physiol, January 1, 2005; 288(1): L159 - L166. [Abstract] [Full Text] [PDF]

				S. Ito, E. P. Ingenito, S. P. Arold, H. Parameswaran, N. T. Tgavalekos, K. R. Lutchen, and B. Suki Tissue heterogeneity in the mouse lung: effects of elastase treatment J Appl Physiol, July 1, 2004; 97(1): 204 - 212. [Abstract] [Full Text] [PDF]

				F.G. Salerno, A. Fust, and M.S. Ludwig Stretch-induced changes in constricted lung parenchymal strips: role of extracellular matrix Eur. Respir. J., February 1, 2004; 23(2): 193 - 198. [Abstract] [Full Text] [PDF]

				K. K. Brewer, H. Sakai, A. M. Alencar, A. Majumdar, S. P. Arold, K. R. Lutchen, E. P. Ingenito, and B. Suki Lung and alveolar wall elastic and hysteretic behavior in rats: effects of in vivo elastase treatment J Appl Physiol, November 1, 2003; 95(5): 1926 - 1936. [Abstract] [Full Text] [PDF]

				H. Sakai, E. P. Ingenito, R. Mora, S. Abbay, F. S. A. Cavalcante, K. R. Lutchen, and B. Suki Hysteresivity of the lung and tissue strip in the normal rat: effects of heterogeneities J Appl Physiol, August 1, 2001; 91(2): 737 - 747. [Abstract] [Full Text] [PDF]

				P. V. Romero, W. A. Zin, and J. Lopez-Aguilar Frequency characteristics of lung tissue strip during passive stretch and induced pneumoconstriction J Appl Physiol, August 1, 2001; 91(2): 882 - 890. [Abstract] [Full Text] [PDF]

				T. EBIHARA, N. VENKATESAN, R. TANAKA, and M. S. LUDWIG Changes in Extracellular Matrix and Tissue Viscoelasticity in Bleomycin-induced Lung Fibrosis . Temporal Aspects Am. J. Respir. Crit. Care Med., October 1, 2000; 162(4): 1569 - 1576. [Abstract] [Full Text] [PDF]

				H. Yuan, S. Kononov, F. S. A. Cavalcante, K. R. Lutchen, E. P. Ingenito, and B. Suki Effects of collagenase and elastase on the mechanical properties of lung tissue strips J Appl Physiol, July 1, 2000; 89(1): 3 - 14. [Abstract] [Full Text] [PDF]

				R. Tanaka and M. S. Ludwig Changes in viscoelastic properties of rat lung parenchymal strips with maturation J Appl Physiol, December 1, 1999; 87(6): 2081 - 2089. [Abstract] [Full Text] [PDF]

				F. G. SALERNO, P. PARE, and M. S. LUDWIG A Comparative Study of Elastic Properties of Rat and Guinea Pig Parenchymal Strips Am. J. Respir. Crit. Care Med., March 1, 1998; 157(3): 846 - 852. [Abstract] [Full Text] [PDF]

				H. Yuan, E. P. Ingenito, and B. Suki Dynamic properties of lung parenchyma: mechanical contributions of fiber network and interstitial cells J Appl Physiol, November 1, 1997; 83(5): 1420 - 1431. [Abstract] [Full Text] [PDF]