Studies on the phospholipids in tracheal aspirate from normal full term newborn infants. Comparison with amniotic fluid.

The phospholipids in tracheal aspirates from normal full term newborn infants were studied and compared to the phospholipids present in the corresponding amniotic fluids. The same classes of phospholipids were recovered from both fluids, i.e. lysophosphatidylcholine (LPC), phosphatidylserine (PS), phosphatidylinositol (PI), sphingomyelin (S), phosphatidyldimethylethanolamine (PDME), phosphatidylethanolamine (PE), polyglycerophosphatides (PGP), phosphatidic acids (PA) and two different species of phosphatidylcholine (PC-1 and PC-2). Except for PA, the proportion as well as the fatty acid composition of each of these phospholipids was similar in tracheal aspirates and in amniotic fluids. The predominant fraction (PC-1) was the most saturated one. PI, PDME, LPC and S were, like PC-1, predominantly constituted by saturated fatty acids and accounted together for a concentration equivalent to that of PC-1. Since tracheal aspirate originates from the lung, these data suggest that the pulmonary surfactant activity in normal full term newborn infants results not only from the presence of PC-1, but also from that of PI, PDME, LPC and S.