EFFECT OF SULFUR-DIOXIDE ON MUCOCILIARY ACTIVITY AND CILIARY BEAT FREQUENCY IN GUINEA-PIG TRACHEA

The effects of 30 min exposure to sulfur dioxide on mucociliary activi ty (MCA) and ciliary beat frequency (CBF) were studied in 31 guinea pi g tracheas. MCA was measured by recording the light reflected from cil iated mucous membranes using an infrared bar code reader. CBF of singl e ciliated cells obtained by brushing was measured with phase-contrast microscopy. Each tracheal sample was exposed to SO2 at concentrations ranging from 2.5 to 12.5 ppm, or to air for control purposes. MCA and CBF were measured before and immediately after gas exposure. A reduct ion in mean MCA of 63% (P = 0.0007) and statistically insignificant ch anges in CBF (P > 0.05) were recorded at concentrations of 2.5 ppm SO2 . Higher SO2 concentrations caused a further impairment of MCA as well as a dose-dependent decrease in CBF (P = 0.002). A concentration of 1 2.5 ppm SO, induced a decrease from baseline values of approximately 8 0% in mean MCA and of roughly 70% in mean CBE This study demonstrates a dose-dependent SO2-induced decrease in MCA of guinea pig tracheas. T he decrease in MCA was associated with an impairment of CBF only at SO 2 concentrations higher than 5.0 ppm.