The effects of Ma-Xing-Gan-Shi-Tang on respiratory resistance and airway leukocyte infiltration in asthmatic guinea pigs

Ma-Xing-Gan-Shi-Tang (MXGST), a traditional Chinese medicine, has been used in treatment of the bronchial asthma for several centuries. However, the therapeutic mechanisms of this Chinese medicine are still far from clear. To understand the mechanism of anti-asthmatic property of MXGST, a guinea pig model of allergic asthma was used to investigate the effects of MXGST on Dermatophagoides pteronyssinus-induced early and late asthmatic responses and airway inflammation, and examine direct beta2-adrenoceptor agonist activity in guinea-pig isolated trachea. Administration of MXGST (10 g/kg) extracts significantly inhibited the antigen induced immediate asthmatic responses (IAR) in actively sensitized guinea pig. MXGST caused concentration-dependent relaxation in strips of guinea pig trachea contracted with carbachol, and ICI-118551, a selective beta2-adrenoceptor antagonist, significantly inhibit the relaxation caused by MXGST. Furthermore, examination of bronchoalveolar lavage fluid (BALF) revealed that MXGST significantly inhibited the increase in neutrophil in the airway at 1, 6 and 24 hr after antigen challenge. Histopathologic examination results showed that MXGST suppressed the neutrophil infiltration into lung tissue. In conclusion, we suggest that the anti-asthmatic effects of MXGST are mainly due to its stimulation of beta2-adrenoceptors on bronchial smooth muscle and its anti-inflammatory ability to inhibit the neutrophil into the airway. The precise mechanism of action of MXGST in asthma remains to be elucidated.