Alveolar lavage and lavaged lung tissue phosphatidylcholine composition during fetal rabbit development

Pulmonary surfactant, the major surface-active component of which in the adult is dipalmitoylglycerophosphocholine, can be obtained by lavaging lungs with physiological saline. We have previously shown that there is an increase in the amount of phosphatidylcholine in fetal rabbit lung lavage during the latter part of gestation. We have now measured the amount of disaturated phosphatidylcholine as well as the fatty acid composition of phosphatidylcholine in lung lavage from fetal rabbits during the period 27 days' gestation to full term (31 days). There was no developmental change in the amount of disaturated phosphatidylcholine during the period examined. About 50% of the total phosphatidylcholine was disaturated which is approximately the same as in adult rabbit lung lavage. The fatty acid composition, however, did change. There was an increase in the amount of 16:0 from about 20% of the total fatty acids in phosphatidylcholine at 27-28 days to about 60% at full term, after birth, and in the adults. There was a corresponding decrease in the amounts of 14:0, 18:0, and longer chain fatty acids, most of which were saturated. In the lavaged lung tissue, there was a 2.6-fold increase in the percentage of phosphatidylcholine which was disaturated during the period 27-31 days' gestation. It had not decrease to the adult value 24 hr after birth.