[In vitro studies of modification of mucociliary clearance by guinea pig tracheas by exposure to air pollutants of sulfur or nitrogen dioxide].

We studied the effect of sulfur dioxide (SO2) and nitrogen dioxide (NO2) on mucociliary activity (MCA) and ciliary beat frequency (CBF) in 63 guinea pig tracheas. The tracheas were placed in a gas cylinder and exposed for 30 minutes to SO2 concentrations ranging from 2.5 to 12.5 ppm or to NO2 concentrations ranging from 3.0 to 15.0 ppm. Control experiments were performed with exposure of the tracheas to synthetic air. MCA was measured by recording the light reflected from ciliated mucous membranes using an infrared barcode reader and CBF using video-interference microscopy. The exposure to 2.5 ppm SO2 caused a reduction in mean MCA of 63% and no significant changes in CBF. Higher SO2 concentrations caused a further impairment of MCA as well as a dose-dependent decrease in CBF. 10.0 or 12.5 ppm SO2 induced a decrease from baseline values to approximately 20% in MCA and to roughly 30% in mean CBF. The exposure to NO2 at concentrations ranging from 3.0 to 15.0 ppm did not induce any changes in MCA or CBF of the guinea pig tracheas. Our results show that exposure to SO2 for 30 minutes is able to depress the mucociliary clearance of guinea pig tracheas, whereas the exposure to equivalent NO2 concentrations for the same time do not alter the mucociliary transport.