Rat lungs as affected by an acute exposure to an increased level of carbon dioxide in the ambient air.

Abstract

Changes in lung characteristics of healthy adult male rats were studied following a 24-hr exposure to 15% CO2 in air. The animals were weighed before and after the exposure period. Following the CO2-exposure, the lungs of the rats were removed and their weights were determined. Continuous pressurevolume curves including inflation and deflation first with air and then with 0.9% saline were recorded from the excised lungs. The average gain in body weight of the control rats during the 24-hr period was 9 g while the CO2-exposed rats lost 24 g. The mean values for wet and dry lung weights and trapped gas volume in the lung were essentially the same in the two groups of rats. Similarly the lung tissue compliance both during inflation and deflation was not significantly different between the two groups of animals. One characteristic feature of the total lung compliance for 69% of the CO2-exposed rats was a progressive decrease in compliance on successive runs associated with a decrease in the area described by the compliance curves. These would suggest instability of lung alveoli in these rats with a significant alteration of their surfactant activity.