The purpose of this study was to investigate the effects of ephedrine, an alpha,beta-adrenoceptor agonist, on the regulation of human nasal ciliary beat frequency (CBF). Changes in (cultured) human nasal CBF in response to 0.25, 0.5, 1.0 and 2.0% ephedrine were quantified by using high-speed (240 frames per second) digital microscopy combined with a beat-by-beat CBF analysis. At similar to 25 degrees C, we found that ephedrine induces an instant and moderate increase in human nasal CBF followed by an inhibitory response. With concentrations ranging from 0.25 to 2.0%, while the increment is independent of ephedrine concentration, the inhibitory effect is dependent on the concentration of ephedrine. Based on these results we propose that the clinically used concentration of ephedrine, 0.5%, has maximum stimulatory effect without obvious inhibitory effect on (cultured) human nasal CBF. Copyright (C) 2008 S. Karger AG, Basel.