Toxicity of cadmium oxide instilled into the rat lung. II. Inflammatory responses in broncho-alveolar lavage fluid

Biochemical and cytological responses in the broncho-alveolar lavage fluid were investigated after instillation of cadmium oxide (CdO) or cadmium chloride (CdCl2) into the rat lung. Although biochemical responses of the lung to CdO were similar to the CdCl2-exposed lung, cytological response was more sensitive to CdO than CdCl2. Increases of lactate dehydrogenase, protein content and number of cells in the lavage fluid were proportional to the dose over the range of 0.5-10 micrograms Cd/rat. beta-Glucuronidase activity in the fluid increased with dose at low doses of Cd, but the activity did not continue to increase above 2 micrograms Cd/rat. A dose-response profile of phosphorus content in the lavage fluid, which might indicate amount of surfactant produced by Type II cells was similar to that observed for beta-glucuronidase in CdO-treated rats. Thus, tolerable level of instilled CdO for the rat lung was about 2 micrograms Cd/rat.