"Alveolar" and whole lung phospholipids of the developing fetal lamb lung

Abstract

Quantative and qualitative studies were performed on the lung phospholipids removed from 17 fetal lambs by 2 techniques: by sequential lung washings ("alveolar" phospholipids) and from whole lung homogenates (tissue phospholipids). Surface-active material is present in the alveoli of the term lamb fetuses prior to the onset of respiration. The alveolar phospholipids differ in several respects from lung tissue phospholipids. Analysis of the positional specificity of the alveolar phosphatidyl choline revealed a predominance of dipalmityl phosphatidyl choline in term fetuses. Negligible amounts of alveolar phosphatidyl choline were obtained from immature fetuses and the lung washings lacked surface activity. Alveolar phosphadidyl choline increased 50-fold from immature to transitional fetuses and another 4-fold to term fetuses. The increase in alveolar disaturated phosphatidyl choline content during gestation correlated well with the appearance of surface activity. Phosphadityl dimethylethanolamine was recovered from the lung washings of transitional and term fetuses.