Developmental changes in molecular species of phosphatidic acid in rat lung and liver during the perinatal stage

A new and sensitive method for the determination of the molecular species of phosphatidic acid was developed. The developmental profiles of the structural heterogeneity of phosphatidic acid in rat lung and liver are presented. The individual molecular species of phosphatidic acid at different stages of development were analyzed as [14C]dimethylphosphatidates. The content of phosphatidic acid gradually increased from 20 to 40 nmol/g wet tissue during development of both lung and liver. The relative distribution of the disaturated species of lung phosphatidic acid accounted for 10.1 +/- 2.4% at -2 days of gestation and slightly decreased at -1 day and 1 day after birth (8.4 +/- 1.1%), then increased significantly to the adult level of 14.6 +/- 3.2%. The developmental pattern of the disaturated species of phosphatidic acid was not similar to that of diacylglycerol or phosphatidylcholine. On the other hand, the relative distribution of the disaturated species of liver phosphatidic acid did not change (4.1-6.0%) during development. The level of the disaturated species of phosphatidic acid was significantly higher in lung than in liver at any stage of development. The overall results strongly suggest that disaturated phosphatidic acid could be effectively formed via the de novo pathway in fetal as well as in adult lung.