Maturation of the fetal lung II. Effect of hyperoxia on phosphatidic acid phosphatase, pyruvate kinase and superoxide dismutase activity in the newborn rat lung.

Oxygen-induced lung toxicity was studied in newborn rats. Three-day-old rats were exposed to 85-90% oxygen or air for 48 h. The activity of pulmonary antioxidant defenses, as measured by the activity of superoxide dismutase (SOD), showed a progressive increase in activity. The activity of phosphatidic acid phosphatase (PAPase) showed a statistically significant decrease in the oxygen-poisoned lung. In the activity of pulmonary pyruvate kinase no significant change occurred. After two days of oxygen exposure (FiO2 085-0.9) marked histological changes appeared including an increased number of interstitial cells, atelectasis, pulmonary oedema, diminution of lamellar content, loose lamellar bodies and increasing tubular myelin in the alveolar space.