SUBSTANCE-P AND CILIARY BEAT OF HUMAN UPPER RESPIRATORY CILIA IN-VITRO

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 (CBE) of the human upper respiratory tract. Ciliated epithelium of human adenoid tissue was use d in the experiments. The CBF was measured by means of a computer-assi sted photoelectric method. Substance P(10(-8) to 10(-5) mol/L, n = 7) showed a small but statistically significant dose-dependent decrease i n CBF. On perfusion with SP(10(-8) to 10(-5) mol/L, n = 8) in combinat ion 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.