Fig. 2. Effect of propofol (0–300 μm) on ciliary beat frequency (CBF) in cultured rat tracheal epithelial cells. Immediately after the baseline CBF was determined, vehicle (0.1% dimethyl sulfoxide) or various concentrations of propofol were added at time 0, and CBF was measured 25 min thereafter. Values are expressed as a percentage change from baseline CBF (baseline = 100%) and represent the mean ± SD. There is a significant difference among the groups (P < 0.0001). *P < 0.05, significantly different from vehicle; †P < 0.05, significantly different from 1 μm propofol.