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On stimulation of trigeminal nerve endings, neuropeptides are released into the nasal mucosa. Among these neuropeptides is substance P(SP). In this study, we determined the effect in vitro of SP, as well as SP together with thiorphan, a blocker of the SP-degrading enzyme neutral endopeptidase, on the ciliary beat frequency (CBF) of the human upper respiratory tract. Ciliated epithelium of human adenoid tissue was used in the experiments. The CBF was measured by means of a computer-assisted photoelectric method. Substance P(10(-8) to 10(-5) mol/L, n = 7) showed a small but statistically significant dose-dependent decrease in CBF. On perfusion with SP (10(-8)) to 10(-5) mol/L, n = 8) in combination with thiorphan, no statistically significant effect was found. We conclude that SP does not have a direct effect on ciliary activity to such an extent that it will affect mucociliary transport in vivo.

The aim of this study was to explore the usefulness of two different in vitro models for studying the function of human upper respiratory cilia, i.e. cell suspension cultures of human upper airway epithelium, and ciliated adenoid epithelium. Ciliary beat frequency (CBF) and signal consistency (SC), as parameters of ciliary function, were measured by a computerized photo-electrical method. Measurements after one week revealed that CBF of ciliated aggregates from cell suspension cultures had deteriorated to a mean of 5.8 Hz. In the subsequent period, it remained at this rather low and non-physiological level. SC decreased too, although not as dramatically. These results indicate that ciliated aggregates from cell suspension cultures cannot be used for human ciliary function experiments in vitro. On the other hand, in ciliated adenoid epithelium, CBF remained constant for a period of 5 h, although SC decreased after 30 min. Because of this result and the fact that ciliated adenoid epithelium is easily obtainable, we regard this material as suitable for studying human ciliary beat in vitro.

Decreased mucociliary transport can occur in patients with type I (IgE-mediated) allergic rhinitis or allergic asthma. This study investigated if the allergic mediators histamine and leukotriene C4 (LTC4) could interfere with ciliary beat frequency (CBF) of in vitro human upper respiratory cilia and eventually result in decreased mucociliary transport. Ciliated epithelium of human adenoid tissue was used in the experiments and CBF was determined using a computer-assisted photoelectric method. Histamine in concentrations of 10(-6) - 10(-3) M (n = 12) and LTC4 as 10(-9) - 10(-6) M solutions (n = 10) showed no statistically significant dose-dependent effect on CBF in vitro.