Objective: To study the mechanism of herbal application along meridians for treatment and prevention of asthma by using serum pharmacological test to observe the effects of serum containing herbs against the constriction of tracheal spiral strips induced by acetylcholine chloride (Ach).

Methods: Guinea pigs were randomly divided into normal control group, normal saline (NS) application group, aminophylline application group, aminophylline injection group, 1-day herb application group, 7-day herb application group and 14-day herb application group. Asthma was induced by Hutson's method in guinea pigs except the normal control group. Guinea pigs in herb application groups were treated by external application of a compound herbal medicine 60 min once every day. Guinea pigs in NS application group were treated by external application of NS. Guinea pigs in the two aminophylline-treated groups were treated by external application and intraperitoneal injection of aminophylline at a dose of 400 mg/kg, respectively. The guinea pigs were killed and the sera were obtained after 1-day, 7-day and 14-day treatment in the three herb application groups, 7-day treatment in the NS application group, the aminophylline application and injection groups, respectively. Serum pharmacological method was used to do the experiment, the effects of different sera on the constriction of tracheal strips were observed, and the constriction rates were calculated.

Result: The serum containing herbs had an effect in reducing the constriction of tracheal spiral strips induced by Ach, and the effect was similar to that of the serum obtained from the aminophylline injection group. The constriction rate of the tracheal spiral strips was decreased when herbal application treatment was prolonged within a period of time, and it became stable when herbal application treatment was between 7-14 days. The constriction of tracheal spiral strips induced by Ach could be reduced remarkably when it was previously treated by serum containing herbs. 

Conclusion: The anti-acetylcholine function with a time-dependent effect is one of the mechanisms of herbal application treatment along meridians for asthma, and furthermore, herbal application treatment along meridians might be useful for preventing asthma.

Key words: asthma, Chinese herbal drugs, acetylcholine chloride, aminophylline