Effect of atropine on ciliary beat in human upper respiratory tract epithelial cells

The mucociliary apparatus is a fundamental element among the defensive mechanisms of the airways. In man, average ciliary beat frequency (CBF) has been reported to be between 600 and 1,000 beats/min and does not vary significantly at different sites along the respiratory tract. Ciliary function is altered by numerous factors, including temperature, pH, cigarette smoke, drugs, and alcohol. The aim of the present study was to evaluate whether intravenous (i.v.) infusion of atropine alters CBF. We studied nine patients (six females and three males, mean age 42.9 years) with otosclerosis, a nonrespiratory disease. All patients were scheduled for surgical stapedectomy. In all patients, nasal brushing was performed before and 20 min following i.v. injection of 0.5 mg atropine sulphate. The cellular samples, maintained viable in tissue medium, were observed under a microscope and filmed. A quantitative evaluation of ciliary activity was obtained by playing the film back in slow motion. The mean CBF value prior to atropine infusion in the nine patients studied was 588.12 (±53.29 SD) beats/min. After infusion of atropine, mean CBF was 442.33 (±52.82 SD) beats/min. The mean percentage drop in CBF following atropine infusion was 24.79% (t=5.82, p<0.001). Our data show a drop in in vitro CBF following atropine infusion which, presumably, reflects a fall in the in vivo efficacy of mucociliary transport. Atropine treatment determined a loss in CBF that was inversely correlated with increasing age.