Nicotine increases ciliary beat frequency by a direct effect on respiratory cilia

Summary

We studied the direct effects of nicotine on the ciliary beat frequency (CBF) undisturbed by interference from mucus secretion by using epithelial strips from ferret tracheae which contain no goblet cells and, because the glands were left behind in the submucosa, no gland tissue either. Strips were studied in a chamber perfused with medium M-199 at 37° C at a perfusion rate of 1.6 ml min⁻¹ using a perfusion pump (Braun, Melsungen). CBF was determined photometrically, the signal being subjected to a fast Fourier transformation. We measured CBF continuously for 10 min (5 min with and 5 min without perfusion). Under baseline conditions without nicotine, it decreased from 23.4 ± 0.8 to 22.2 ± 0.5 Hz during perfusion and increased from 22.0 ± 0.8 to 23.3 ± 0.8 Hz during the subsequent period without perfusion. Nicotine increased CBF transiently, i.e., the effect was demonstrable only during perfusion, being strongest during the first 3 min of perfusion. At 10⁻⁵M, the increase in CBF was significant only during the 3rd minute, but at 10⁻⁴ and 10⁻³M, CBF was elevated significantly throughout most of the perfusion period compared with control tissues perfused with medium M-199 only. Thus, at 2 min, CBF was 22.8±0.6 (x±SE) in tissues perfused with medium M-199 only but was 24.3 ± 0.8 Hz (NS, Student's unpaired t-test), 26.6+0.5 Hz (P= 0.001), and 26.8±1.2 Hz (P=0.01) in tissues perfused with 10⁻⁵ 10⁻⁴ and 10⁻³M nicotine (dissolved in medium M-199), respectively. We conclude that nicotine stimulates CBF and that the effect is not mediated by a nicotine-induced in rease in mucus secretion.