Effects of oxygen radicals on ciliary motility in cultured human respiratory epithelial cells

There are few reports about direct effects of specific oxygen products on ciliary function because of their instability and reactivity. We investigated the direct effects of superoxide anion (O2-) and of hydrogen peroxide (H2O2) on the ciliary function of human respiratory epithelial cells, using monolayer cell cultures, high speed video analysis of frequency (CBF), amplitude (CBA), and coordination of ciliary beats and evaluating the surface structural changes of ciliated cells at the same time. 10(-2) M H2O2 decreased ciliary beat activity. The CBF was 36.5 +/- 4.4% and the CBA was 51.0 +/- 3.8% of the baseline (time = 0) after 5 min (all p < 0.001). Catalase (2 micrograms/ml) abolished the ciliotoxic effect of H2O2. The O2- produced by reaction of xanthine (0.06 mM)-xanthine oxidase (0.04 U/ml) caused a temporary rapid increase of 26.8 +/- 1.7% in CBF and an increase of 42.5 +/- 4.1% in CBA after 15 sec (all p < 0.001). Superoxide dismutase significantly reduced these increases. Results indicated that O2- activated ciliary function with a temporary increase in O2(-)-production. This suggests that the removal of H2O2 from the O2- reaction is important in improving mucociliary clearance in excessive oxygen metabolites.