Application of the determination of adenylate cyclase activity to the studies of Chai Hu has been reported. The results show that this method can be used for the determination of activation

inhibition

and activation/inhibition dual action of drugs on adenylate cyclase; and

with the pre-incubation with receptor blockers it can be used to investigate the mechanism by which the drugs affected the activity of adenylate cyclase. The result of the enzymatic activity determination is consistent with that of the biological effect. By using this method

some interesting results discovered were in the studies of effective fractions of Chai Hu.