Effects of ursolic acid, betulin and sulfur-containing compounds on mucin release from airway goblet cells.

In this study, we investigated whether ursolic acid, betulin and 2 kinds of sulfur-containing compounds - NAC and MESNA - affect mucin release from airway goblet cells and compared the possible activities of these agents with the inhibitory action on mucin release by PLL and the stimulatory action by ATP. Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled using 3 H-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on 3 H-mucin release. The results were as follows : ursolic acid, betulin, MESNA and NAC increased mucin release (40- 50% above control) at the highest concentrations (10 -5 M - 10 -3 M). We conclude that ursolic acid and betulin can stimulate mucin release by directly acting on airway mucin-secreting cells and suggest that these agents be further investigated for the possible use as mucoregulators in the treatment of chronic airway diseases.