The effect of betamethasone on pressure-volume characteristics of nonfetal rat lungs.

Abstract

Betamethasone was administered to rats for 28 days, and body weight, lung weight, and descending pressure-volume relations were measured in their excised lungs. In rats treated with corticosteroid, lung and body weights increased less rapidly than in control rats, but the ratio of lung wet weight to body weight and the per cent dry weight remained the same in both groups. The absolute lung volume was significantly greater at each pressure in the control rats; but when expressed per lung weight, the lungs of rats treated with corticosteroid held more air. When corrected for lung size, the only difference in the lung pressure-volume curves between groups existed at transpulmonary pressures of 0 and 5 cm H2O, where the lungs of the rats treated with betamethasone contained more volume, whether inflated with air or with saline. We concluded that betamethasone administered to nonfetal rats has little influence on the lung's pressure-volume characteristics, which cannot be ascribed to differences in lung size.