Carbocisteine improves the mucociliary transport rate in rats with SO2-induced bronchitis

In order to study the effect of carbocisteine on the mucociliary function of the respiratory tract, we performed a double-blind study on rats with SO2-induced (400 ppm) hypersecretion. During the experimental bronchitis, the treated group of rats received carbocisteine through a stomach tube at a dose level of 500 mg/kg for 15 days, whereas the untreated group of rats received distilled water. After killing the rats, and following lung excision, the respiratory mucus was scraped off and collected by using a glass capillary. The mucus degree of purulence was macroscopically estimated and the mucus transport rate was measured by using the frog palate technique. The mean mucus relative transport rate, measured on the frog palate, was 0.60 +/- 0.17 in the untreated group and was significantly higher (P < 0.01) in the treated group (0.73 +/- 0.14). Carbocisteine also significantly altered (P < 0.01) the mucus macroscopical aspect, leading to a decrease in the number of rats with purulent mucus. These results suggest that carbocisteine maintains an efficient mucus transport rate, leading to a less infected respiratory tract.