Immediate decline in DNA synthesis in neonatal rat lung caused by exposure to 100% oxygen

Oxygen therapy in preterm infants is associated with bronchopulmonary dysplasia, but the relative importance of oxygen toxicity as compared to adverse effects of intubation and mechanical ventilation, remains uncertain. In freely-breathing neonatal rats, exposure to 100% oxygen for as little as 2 hr produced a significant reduction in lung DNA synthesis, evaluated by [3H]thymidine incorporation, without a concomitant effect on [3H]leucine incorporation into protein. These results indicate that hyperoxia has a selective deleterious effect on mitosis in developing lung.