Alveolar pre-type II cells from the fetal rabbit lung: effect of confluence on the production of disaturated phosphatidylcholine.
Pre-type II alveolar cells isolated from the fetal rabbit lung on the 24th gestational day have been maintained in vitro for 14 days in a chemically defined medium supplemented with hormone-stripped serum. These cells replicate in culture. Measurement of the incorporation of [14C]choline into cellular disaturated phospholipid indicated that those cells grown in vitro under standard conditions for 8 days (pre-confluent) incorporate the radioactive precursor at a similar rate to cells maintained for 14 days (post-confluent). Both dexamethasone and serum-free medium conditioned by monolayer cultures of fetal rabbit lung fibroblasts stimulated [14C]choline incorporation into disaturated phosphatidylcholine (PC) by the pre- and post-confluent cultures after 24 or 48 h of exposure: the conditioned medium was more effective than the steroid. These treatments had little effect on choline incorporation into disaturated phosphatidylcholine of preconfluent cells during the first 12 h. A marked response occurred by 24 h after which the labelling of disaturated phosphatidylcholine plateaued. In contrast, with post-confluent cells labelling of disaturated PC increased in a more linear fashion and only plateaued after 72 h. Determination of the ratio of incorporation of [14C]choline into disaturated versus unsaturated phospholipid indicated that serum-free medium conditioned by monolayer cultures of fetal lung fibroblasts specifically increased the level of radioactive precursor in the disaturated phospholipid in both the pre- and post-confluent cell monolayers.
D000818:Animals; D002250:Carbon Radioisotopes; D002455:Cell Division; D002478:Cells, Cultured; D002794:Choline / Q000378:metabolism; D005333:Fetus; D007700:Kinetics; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000096:biosynthesis*; D011817:Rabbits
D002250:Carbon Radioisotopes; D010713:Phosphatidylcholines; D002794:Choline