Pulmonary phospholipied biosynthesis and the ability of the fetal rabbit lung to reduce cortisone to cortisol during the final ten days of gestation

Incubation of fetal lung tissue with 0.2 μM ¹⁴C-cortisone revealed a 12-fold increase in the rate of reduction of cortisone to cortisol between day 22 and day 30 of gestation in the rabbit. This increase correlated closely with the increase in the rate of incorporation of ¹⁴C-choline into total lung lipids during the same period. In light of these findings it would seem inadequate to attempt to relate the plasma cortisol concentration alone with the rate of lung maturation. In addition, one would need consider both the plasma concentration of cortisone and the activity of 11β-hydroxysteroid dehydrogenase (11β-HSD) in the lung.