Toxicity of cadmium to the developing lung
The effects of cadmium on the developing lung and pulmonary surfactant were studied. Pregnant rats received subcutaneous injections of cadmium chloride on days 12 to 15 of gestation and were sacrificed throughout late gestation. The treatment resulted in high embryonic mortality and growth regardation. Fetal lung weight was reduced 20 to 30% due to hypoplasia, as the number of lung cells (DNA/lung) but not cell size (protein/cell) was lowered. The ultrastructural development of alveolar epithelium was altered; cytodifferentiation was delayed; and the cytoplasmic inclusions which contain pulmonary surfactant, were reduced in the term fetus. Accumulation of phosphatidylcholine (PC), the major component of pulmonary surfactant, was diminished in the lungs of treated fetuses. The immediate cause of this lowered accumulation was a decreased rate of synthesis of PC from choline. Carbohydrates probably represent a major source of PC precursors and are present in large quantities in the fetal lung as glycogen. The pulmonary glycogen content of cadmium-exposed fetuses was diminished. It is postulated that this is a reason for the lowered rate of PC synthesis. Maternally administered cadmium did not pass through the placenta; thus, the mechanism of fetotoxicity was indirect. Maternal cadmium exposure did result in lowered fetal zinc levels. Coadministration of zinc with cadmium raised fetal zinc concentration to control values and alleviated all fetotoxicity. Fetal zinc deficiency is a possible mechanism for the toxic effects on the developing lung. Several dams were allowed to give birth and their offspring were observed for respiratory problems. Cadmium treatment delayed parturition by about a day. Symptoms of respiratory distress syndrome (RDS) were observed in 11% of the treated neonates. All but one of these individuals died and had lungs with hyaline membranes. This is the only known case of an environmental agent causing neonatal RDS.
- OSTI ID:
- 5102585
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
CADMIUM
TERATOGENESIS
TOXICITY
LUNGS
SENSITIVITY
ANIMAL CELLS
BIOLOGICAL EFFECTS
BIOSYNTHESIS
BUILDUP
CELL MEMBRANES
DNA
EMBRYOS
MAMMALS
MORTALITY
NEONATES
QUANTITY RATIO
RESPIRATION
ANIMALS
BODY
CELL CONSTITUENTS
ELEMENTS
MEMBRANES
METALS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANS
RESPIRATORY SYSTEM
SYNTHESIS
VERTEBRATES
560305* - Chemicals Metabolism & Toxicology- Vertebrates- (-1987)
550200 - Biochemistry
551000 - Physiological Systems