Coordinate increases in the enzyme activities responsible for phosphatidylglycerol synthesis and CTP:cholinephosphate cytidylyltransferase activity in developing rat lung

The enzymes responsible for the biosynthesis of phosphatidylglycerol, CTP:phosphatidate cytidylyltransferase, CDP-diacylglycerol: glycerophosphate phosphatidyltransferase and phosphatidylglycerophosphate phosphatase demonstrated a coordinate increase in activity in fetal rat lung at term when the demand for pulmonary surfactant increases. The activity of CTP:cholinephosphate cytidylyltransferase, the enzyme responsible for CDP-choline production also increased in the perinatal period. The activity of cholinephosphate cytidylyltransferase in fetal and neonatal cytosol was stimulated by the addition of phosphatidylglycerol but no effect was noted with cytosol from adult lung. These results are consistent with the suggestion that the activity of cholinephosphate cytidylyltransferase, a potential rate-determining enzyme in pulmonary phosphatidylcholine synthesis, may be regulated in the perinatal period both through an activation by phosphatidylglycerol and by an increase in total enzyme units.