Effects of Ding‐Chuan‐Tang on Bronchoconstriction and Airway Leucocyte Infiltration in Sensitized Guinea Pigs

Abstract

Ding‐Chuan‐Tang (DCT), a traditional Chinese medicine, has been used in treatment of the bronchial asthma for several centuries. However, the therapeutic mechanism of these Chinese medicine are still far from clear. To understand the mechanism of antiasthmatic property of DCT. A guinea pig model of allergic asthma was used to investigate the effects of DCT on ovalbumin‐induced early and late asthmatic responses and airway inflammation, particularly the extent of eosinophil infiltration, and examine it direct β2‐adrenoceptor agonist activity in guinea‐pig isolated trachea. We had used three different protocals in ovalbumin sensitized guinea pigs by administrating 10 g/kg of DCT extracts to sensitized guinea pigs 30 min before antigen challenge (group I), 5 hr after antigen challenge (group II) and 2.5 g/kg once daily from the day of sensitization to the day of challenge. Our result showed that administration of DCT singificantly inhibited the antigen induced immediate asthmatic responses (IAR) in group I and inhibited both IRA and late asthmatic responses (LAR) in actively sensitized guinea pig in group III. DCT caused concentration‐dependent relaxations in strips of guinea pig trachea contracted with carbachol, however ICI‐118551, a selective β2‐adrenoceptor antagonist, didn't significantly competitively inhibit the relaxations caused by DCT. Furthermore, examination of bronchoalveolar lavage fluid (BALF) revealed that DCT significantly inhibited the increase in percent of eosinophils in the airway after antigen challenge in three group. Histopathologic examination showed DCT suppressed the eosinophil infiltration into lung tissue. These results suggest that the antiasthmatic effect of DCT is mainly due to its bronchodilatation effect and its ability to inhibit the eosinophil into the airway and there is prophylactic effect of DCT on allergen‐induced airway inflammation.