Effect of amiloride on human bronchial ciliary activity in vitro

Amiloride (AM) reduces mucociliary transport in the frog palate in vitro preparation, whereas in vivo inhalation of AM enhances mucociliary and cough clearance in cystic fibrosis patients. AM influences the bioelectric properties of the respiratory mucosa, and since electrical activity and ciliary activity are strictly related in the beating cell, an effect on ciliary function cannot be excluded. We have, therefore, investigated the effect of AM (10(-7) to 10(-3) M) in vitro on the ciliary activity of ten samples of healthy human bronchial epithelium at 37 degrees C. The baseline ciliary beat frequency was 13.7 +/- (SD) 1.0 Hz. At concentrations of AM of 10(-4) and 10(-3) M, small statistically significant (p less than 0.01) increases in ciliary beat frequency were recorded only after 1 min of exposure to the drug, with changes of +8.2 and +7.6%, respectively. We conclude that (1) AM affects the ciliary activity of the beating cell, but (2) because of the weakness and short duration of the effect, it is unlikely that AM plays a major role on mucociliary transport.