We investigated the extent of the influence of maternal diabetes on the phospholipid composition and exchange activity of the neonatal lung alveolar surfactant. The results show that each phospholipid fraction (as well as the total phospholipid content) of the surfactant of neonates with diabetic mothers are decreased to about 30% of the control values. Phosphatidylcholine and phosphatidylglycerol, which are the most important surface active phospholipid fractions, were decreased to 27% and 34% respectively. In lung tissue of the neonates with diabetic mothers, all phospholipid fractions were increased. We found that the phosphatidylcholine-exchange activity in the alveolar surfactant does not exist in neonates with diabetic mothers. This inhibited phospholipid-exchange activity may be the reason for the decrease in the surfactant phospholipids and their increase in the lungs of neonates with diabetic mothers. The cholesterol content in the surfactant of such neonates decreased by almost half in comparison with the controls, while in lung tissue it remained unchanged. Producing an experimental respiratory distress syndrome could permit to study more deeply the causes which provoke it and the accompanying metabolic changes.
