Increased Mucociliary Transport by Cholinergic Stimulation

Abstract

Tracheobronchial clearance in man was studied after inhalation of a test aerosol of 6μmoles Teflon particles (density 2 gm/cu cm) tagged with technetium 99 M and subsequent external measurement of the radioactivity in the lungs for two hours. Clearance, salivary secretion, and heart rate were determined in eight healthy subjects after administration of saline intramuscularly, or subcutaneously, bethanechol chloride (5 to 7.5 mg), subcutaneously, and methylscopolamine nitrate (0.5 mg), intramuscularly, respectively immediately after the inhalation of the test aerosol. Bethanechol produced an increase in clearance and salivary secretion but not in heart rate. Methylscopolamine had no significant effect on the clearance but produced a decrease in the salivary secretion and an increase in the heart rate. The results indicate that the basic mucociliary transport is not under the influence of vagal activity to any great extent but that vagal activation will produce an increase in the transport velocity.