Response of the aging hamster lung to elastase injury

The effect of age on the induction of emphysema in hamsters was investigated by administering porcine pancreatic elastase endotracheally to old (18 months of age) and young (4 months of age) hamsters; age-matched untreated animals served as controls. Lung volumes, quasi-static deflation volume pressure relations, and mean linear intercept, an index of alveolar size, were measured. Elastase-treated young hamsters demonstrated an increased volume of air in the lungs at a transpulmonary pressure of 25 cm H2O and an increased mean linear intercept. The lungs of old elastase-treated animals showed less pronounced changes than those of young hamsters in lung volume at transpulmonary pressure of 25 cm H2O and in mean linear intercept. Untreated old hamsters had a larger lung volume at a transpulmonary pressure of 25 cm H2O and an 85% increase in total lung collagen. Age-related alterations in connective tissues may account for the increased resistance of old lungs to injury by pancreatic elastase.