Age-related changes in the static and dynamic mechanical properties of mouse lungs

To investigate the effects of aging on pulmonary mechanical properties in mice, we devised a new experimental apparatus to measure the respiratory impedance of excised lungs in mice and examined age-related changes in both static and dynamic properties. In an accelerated senescence-resistant strain of mice, SAMR1 (Takeda, T., Y. Fukuchi, Y. Uejima, K. Teramoto, T. Oka and H. Orino, J. Am. Geriatr. Soc. 39: 911-919, 1991), ranging from 3 to 24 months of age, static compliance (Cst) as well as total lung capacity increased significantly with age, whereas specific compliance and the K value, as determined by exponential analysis, showed no significant change. In the dynamic study, dynamic compliance (Cdyn) increased significantly with age, whereas the frequency dependence of Cdyn (Cdyn/Cst) did not vary with age. From these results we concluded that lung elasticity, normalized to lung volume, remained constant with age and that the effects of aging on pulmonary mechanics might be solely derived from increases in lung volume in the SAMR1 strain of mice.