Production of cortisol from cortisone by the isolated, perfused fetal rabbit lung

Perfusion of the isolated 26 day fetal rabbit lung with 3H-cortisone resulted in its conversion to 3H-cortisol and release into the perfusate. Little conversion of 14C-cortisol to 14C-cortisone occurred. Quantitative study of homogenized fetal rabbit lung revealed the development of both the cofactor and the enzyme for 11beta-hydroxy steroid dehydrogenase activity between 21 and 29 days gestation. These results suggest increasing production of cortisol from cortisone by the fetal rabbit lung as a function of gestational age. This conversion may be of significance with respect to both lung development and parturition, both events being accelerated by cortisol treatment.