Biosynthesis of phosphatidyl choline during prenatal development of the rat lung.

The biosynthesis of phosphatidyl choline in rat lung during prenatal development is of interest in connection with the mechanisms of functional development of the lung, particularly in relation to the production of lung surfactant and the control of phospholipid synthesis. The process was studied by determination of the ability of fetal and adult lung slices to incorporate choline-methyl-(14)C and methionine-methyl-(14)C into phosphatidyl choline. The incorporation of radioactivity from methionine-methyl-(14)C was low in both adult and fetal lung. There was no apparent change in the incorporation during development. The incorporation of choline-methyl-(14)C into phosphatidyl choline after 60 min of incubation was low for fetal lung at 19 days gestation and increased to adult levels by 22 days gestation. The incorporation of choline-methyl-(14)C into phosphoryl choline was high at 19 days gestation and decreased as development progressed. However, the specific activities of the phosphoryl choline were similar in fetal and adult lung, which suggests that the increase in incorporation of choline-methyl-(14)C into phosphatidyl choline with development results from an increased activity of reactions in the biosynthetic pathway between phosporyl choline and phosphatidyl choline.