Flow induced by biological mucociliary systems

The effects of ethanol on mucociliary clearance

Mucociliary clearance by the in vitro frog palate can be used as a model to study such clearance by mammalian lung. Frog palates bathed in Ringer's solution exhibited a constant mucociliary clearance rate for over 2 hr. When the bathing solution was exchanged for one containing ethanol, the mucociliary clearance rate was detectably inhibited by 300 mg/100 ml (mg%) ethanol and significantly inhibited by 400 (50%) and 500 mg% (67%) ethanol. At a concentration of 500 but not 200 mg%, ethanol significantly increased both the amount and the apparent viscosity of the frog palate mucus secreted in 1 hr. Mucus removed from palates bathed in Ringer's solution containing 500 mg% ethanol had no effect on the mucociliary clearance of palates bathed in Ringer's solution alone, and mucus from palates bathed in Ringer's solution alone failed to restore the mucociliary clearance of palates bathed in Ringer's solution containing 500 mg% ethanol. These results suggest that while mucus secretion and rheology are affected by ethanol, such changes in palate mucus do not account for the ethanol-induced inhibition of mucociliary clearance, but rather that the inhibition is the result of a ciliotoxic action of ethanol. Prior exposure of palates to histamine significantly attenuated the inhibitory effect of 500 mg% ethanol on mucociliary clearance, while 200 mg% ethanol significantly potentiated the inhibitory effect of dopamine. It is concluded that the neurohumoral environment of the ciliated epithelium in part determines the effect a given concentration of ethanol will have on mucociliary clearance.

The role of mucociliary dysfunction in bronchial asthma

Abnormalities of mucociliary function in the airways of patients with bronchial asthma are suggested by the clinical observation of excessive tracheobronchial secretions which are difficult to expectorate and may contribute to bronchial obstruction. Pathologic and functional studies in animals and patients have demonstrated an impairment of mucociliary transport mechanisms, but the pathogenesis of this abnormality is still poorly understood. In patients with allergic asthma, the elaboration of chemical mediators in the lung seems to depress mucociliary function. Although pharmacologic agents which increase mucous transport rates have been identified, more potent stimulators will probably be needed to produce a clinical improvement in patients with bronchial asthma.

Influence of steroid aerosol treatments on the clearance of inhaled gold particles

Female Long Evans rats were used to test the hypothesis that in haled triamcinolone acetonide accelerates the rate of clearance of particles from the lung. Three groups of animals inhaled a radioactive gold aerosol, which functioned as a tracer of respiratory tract clearance, and then were subjected to various inhalation treatments. The group treated with triamcinolone acetonide aerosol showed a significant acceleration in the rate of early clearance, but the total amount of tracer particles cleared in the first day was not significantly increased. Inhaled triamcinolone acetonide appears to accelerate the translocation of foriegn particles from small airways to larger ones, but stimulation of clearance does not appear to be a large effect.