Factors affecting tracheobronchial mucociliary transport

In vivo mucus transport rates were studied in humans and donkeys by external measurement of the rate of clearance of insoluble monodisperse gamma-tagged aerosols. The influence of temperature, environmental toxicants and drugs which affect the autonomic nervous system were studied by determining the changes in clearance produced by them in individual subjects. In donkeys, increased pretest ambient temperature accelerated clearance by greater than 1.7%/ degrees C. Smoking 2-7 cigarettes reduced the duration of bronchial clearance by approximately 50% in both humans and donkeys. Donkeys were exposed to higher doses; with progressive slowing of tracheal and bronchial clearance for greater than 10 cigarettes. HCN, at concentrations up to 1230 ppm, produced only a mild transient slowing of clearance. In man, atropine slowed clearance, while the adrenergic stimulating drugs, isoproterenol and epinephrine, both accelerated it by greater than or equal to 4 times, as did isoproterenol when given subsequent to atropine. The cholinergic stimulating drug methacholine increased mucociliary transport in the the donkey. Administration of a tap water aerosol for 10-15 min in humans increased bronchial clearance rates by approximately 25%.