Disaturated phosphatidylcholine in rat lungs with altered numbers of type II alveolar epithelial cells.

Rats exposed to 85 per cent oxygen for 9 days demonstrated an increase in lung deoxyribonucleic acid (DNA) specific acitvity for [3H]-thymidine and a significant increase in the volume of interstitial and alveolar epithelial cells. This included a 63 per cent increase in the number of Type II alveolar epithelial cells. Lamellar body volume per lung significantly increased in animals exposed to oxygen and was related to the increased number of Type II cells, because lamellar body volume expressed per Type II cell remained relatively constant and was comparable to control values. The concentration of whole lung disaturated phosphatidylcholine also increased significantly, but the concentration of unsaturated phosphatidylcholine did not increase. Concomitantly, there was a significant decrease in [32P]-orthophosphate and [14C]-palmitate disaturated phosphatidylcholine specific activity that was proportional to the increased number of alveolar epithelial Type II cells present.