Abstract
The metabolism of lecithin in fetal lung and liver of rabbit was studied in. comparison with adult tissue by incubation of tissue slices with radioactive precursors. The results are summarized as follows: 1. The marked increase of incorporation of 3H-glycerol and 14C-palmitate into lecithin was observed especially in oligoenoic species at 28 days gestation in the lung, indicating the activation of lecithin synthesis via phosphatidic acid pathway. 2. Using 3H-glycerol and 14C-palmitate, ratio of 14C/3H was higher in lecithin than in either phosphatidic acid or diglyceride at all stages examined in the lung but it was not found in the liver. It suggests that a portion of palmitate is incorporated into lecithin or the glycerol moiety in lecithin is partly eliminated by pathways other than phosphatidic acid pathways. 3. The conversion of 3H-palmitate-labeled lysolecithin to lecithin increased rapidly at 28 days gestation in the lung. The isotope ratio of position-2 to position-1 in lecithin was almost unity at all stages in the lung but it was far lower in the liver at the stages other than early gestational one. The high ratio suggests that the reaction is principally operated by acyl-migration of two molecules of lysolecithin.
