Reaction of cultured adult and fetal lung to prednisolone and thyroxine.

Pulmonary explants from adult mice were cultured for periods up to six days in medium with and without one of the following agents: prednisolone, thyroxine, puromycin, actinomycin. Both DNA synthesis and tritiated palmitic acid uptake were greatly reduced by puromycin and actinomycin, which killed the cultures in six days. Prednisolone accelerated uptake of lipid precursor and decelerated DNA synthesis; thyroxine treated explants were not different from controls. Lamellar bodies were observed only in the epithelial cells of cultured explants exposed to prednisolone. Similarly, cultures of fetal lung exhibited maturation with appearance of lamellar bodies only when prednisolone was administered. The depression of cellular division and the stimulation of palmitic acid uptake with coicident appearance of lamellar bodies in cultures exposed to prednisolone supports the hypothesis that control of the differentiation of alveolar epithelium with synthesis of phospholipid surfactant, is a function of the adrenal cortex.