Ultrastructural changes in rat lungs exposed to combinations of cadmium, zinc, copper, and nickel

The morphological effects of single intratracheal intubation of cadmium oxide (CdO) with oxides of zinc (Zn), copper (Cu), and nickel (Ni) at their threshold limit values on alveolar macrophages and type II cells were studied. The combinations used were: CdO + ZnO (0.1 mg + 5.0 mg); CdO + CuO (0.1 mg + 0.2 mg); and CdO + NiO (0.1 mg + 1.0 mg). Rats sacrificed after one week recovery period showed distinct morphological changes. Alveolar macrophages and type II cells exposed to CdO and ZnO showed an increase in number, shape, and size of vacuolar phagolysosomes. Multivesicular bodies and lamellar bodies were also seen, as well as the lack of distinct nucleoli. The CdO/CuO combination showed an increase in the number of dense vacuolar phagolysosomes and large aggregates of multivesicular bodies. Hypertrophy of mitochondria was also evident in this combination. The CdO/NiO combination showed more distinctive changes compared to the other two combinations in lysosomes, membranous whorls, multivesicular bodies, residual bodies, and number of mitochondria. Our findings using combination exposures of CuO and ZnO with CdO indicate the existence of competitive inhibition resulting in some form of protective action. On the other hand, the CdO/NiO exposure seemed to be additive showing structural modifications, premature aging, faster degeneration, and release of abnormal membrane structures.