Changes in pulmonary connective tissue proteins after a single intratracheal instillation of cadmium chloride in the rat

Changes of soluble and insoluble fractions of pulmonary connective tissue proteins were studied in rats for 2–84 days following a single intratracheal instillation of cadmium chloride (10 μg Cd 2+/lung). A transient decrease in body weight and an immediate increase in lung wet weight (200% of control value, P < 0.01) were observed. Incorporation of [ 14C]proline and its conversion to [ 14C]hydroxyproline in vivo into different soluble and insoluble fractions of connective tissue revealed an increased metabolic turnover elicited by intoxication. A lag in the maturation of collagen into higher functional forms in the early phase of the process was demonstrated. A striking decrease in elastin was found in first 7 days (40–50%). However, this acute damage of pulmonary connective tissue was followed by a permanent increase of collagen and elastin concentration in the later phase of recovery. Histopathologic examination 14–84 days after cadmium instillation confirmed the presence of lesions in pulmonary tissue with an initial inflammation followed by reparatory changes.