Toxic effects of cadmium on the developing rat lung. I. Altered pulmonary surfactant and the induction of respiratory distress syndrome

Abstract

The effects of Cd on the growth of the fetal rat lung and the maturation of the pulmonary surfactant system were studied. Pregnant rats received sc infections of cadmium chloride on d 12–15 of gestation. Animals were sacrificed throughout late gestation. Fetal lungs were assayed for pulmonary surfactant lecithin and sphingomyelin. Some animals were allowed to give birth and the neonates were observed for symptoms of respiratory distress. The treatment resulted in high fetal mortality and growth retardation. Lung‐body weight ratios were reduced by 20–30% in treated fetuses. Pulmonary sphingomyelin content was not affected by the Cd treatment. Lecithin, the most important surfactant component, was reduced in absolute quantity but not in lecithin‐lung weight ratio on the last days of gestation. Parturition was delayed almost a full day by the Cd treatment, and birth weights were reduced. Of the treated neonates, 11% developed respiratory distress syndrome. All but one of these individuals died and had lungs with hyaline membranes. Prenatal exposure to Cd can (1) cause lung hypoplosia, (2) affect pulmonary surfactant, and (3) induce respiratory distress syndrome in term pups.