Comparison of the relaxant effects of alkaloids extracted from Ephedra sinica and E. intermedia in isolated guinea pig trachea

Objective: To compare the relaxant effects of alkaloids extracted from herbaceous stems of Ephedra sinica and E.intermedia in isolated guinea pig trachea.Methods: Ephedra herbs with same weight were used to extract alkaloids,which was used to compare the relaxant effect in isolated trachea strip from guinea pig.The contents of alkaloids were determined by HPLC method.Results: The relaxant effect of alkaloid extracted from Ephedra sinica(20.35%,38.38% and 52.88%) was stronger than that from E.intermedia(12.14%,24.69% and 39.26%),respectively,at the same low,middle and high concentrations.The EC50 values of Ephedra sinica and E.intermedia were 0.111g·L-1 and 1.019g·L-1.Ephedra sinica mainly contained ephedrine,while E.intermedia mainly contained pseudoephedrine.Conclusions: The relaxant effects of alkaloids extracted from Ephedra sinica and E.intermedia are different in isolated guinea pig trachea,and the difference may be related to their diverse ephedrine contents.