Evaluation of excised lung gas volume measurements in animals with genetic or induced emphysema

Emphysema, a leading cause of respiratory disability and mortality in humans, is characterized by destruction of alveolar walls and enlargement of airspaces. Animal studies are critical in understanding the pathogenesis of emphysema. However, current measurements of airspace enlargement and emphysema in small laboratory animals are labor intensive and may not be sensitive enough for measuring alterations in lung function and structure at the early stages of emphysema. In this study, we have investigated the excised lung gas volume (ELGV) measurement as a potential index for determining airspace enlargement in pallid mice with developing emphysema, in tight-skin mice with developed emphysema, or in Wistar rats with emphysema induced by an intratracheal instillation of pancreatic elastase. Our results showed that values of both ELGV per lung and per gram lung tissue were significantly increased in all three emphysema models, compared to control. The ELGV values were correlated well with morphometric evaluation of emphysema. Variations in transpulmonary pressures caused by different termination procedures were critical factors influencing the ELGV values. The present study demonstrates that ELGV measurement is a simple and sensitive method to monitor the development of emphysema.