Effect of premature delivery on rat lung retinol (vitamin A) and retinyl ester stores.

Low plasma retinol (vitamin A) in premature infants has been associated with bronchopulmonary dysplasia. Also, retinol (vitamin A) deficiency is characterized by loss of cilia and squamous metaplasia of the respiratory tract, similar to the histological lesions of bronchopulmonary dysplasia of the premature infant. Recent work showed that the fetal rat lung retinyl palmitate stores were high preterm, but fell abruptly between 21 days of gestation and postpartum. This report extends this observation by showing that lung retinyl palmitate also decreases after cesarean section delivery preterm. Lung retinol and retinyl palmitate in the lungs of 21-day gestation fetuses delivered by cesarean section and stimulated to breath were compared to their in utero littermates. In utero lungs contained 2.2 +/- 0.14 micrograms/g dry weight retinol and 14.9 +/- 0.8 micrograms/g dry weight retinyl palmitate. Lungs from littermates that had been removed from the uterus and breathed on their own for 4 h had lower retinol (1.6 +/- 0.08 micrograms/g) and retinyl palmitate (11.3 +/- 0.4 micrograms/g; p less than 0.01). Fetal lung contains retinyl palmitate stores that are readily mobilized with delivery at term or preterm.