CYTOTOXIC EFFECTS OF NICKEL ON CILIATED EPITHELIUM

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Abstract
The effect of graded concentrations of Ni [environmental pollutant] on ciliary activity in an in vitro model system using isolated hamster tracheal rings was measured and the in vitro findings with in vivo exposures were compared using an organ culture system. Dose-response experiments were conducted for various Ni concentrations and lengths of exposure. In the in vitro model, significant decreases in ciliary activity occurred at concentrations as low as 0.011 mM Ni (0.65 .mu.g of Ni/ml). A dose-response relationship between the concentration of Ni and ciliary action was demonstrated. A range of effects from a significant decrease of 26 beats/min (0.65 .mu.g of Ni/ml) to complete ciliostasis (65 .mu.g of Ni/ml) was observed after 24 h of exposure. Validation of the in vitro results occurred when hamsters were exposed to a NiCl2 aerosol at concentrations of 100-275 .mu.g of Ni/m3. Immediately after the cessation of a 2 h in vivo exposure, a decrease in ciliary activity of 60 and 140 beats/min was observed for animals exposed to 100 and 275 .mu.g of Ni/m3, respectively. The length of time required for recovery from the in vivo exposure to Ni aerosol was determined. Histologic examination of the epithelial cells showed dose-related effects. Ni, either administered to the whole animal or to the tracheal epithelium directly, may significantly decrease the ciliary beating frequency and interfere with the normal functioning of respiratory defense mechanisms, thereby increasing the risk of the host to respiratory infections.