The effect of dauricine on level of TXA2 and cAMP in the rabbi platan-elet was studied. The results showed that dauricine protected signific-tly mice against the sudden death induced by intravenous arachidonic acid in vivo, and that dauricine inhibited the platelet aggregation ind uced by arachi- donic acid, inhibited the production of TXA2 in the plateletand did not change the basic cAMP level in the platelet invitro. These suggested that one of the action mechanism of the inhibition of the platelet aggregation by dauricine was possibly related to the inhibition of the production of TXA2.

It has been shown that dauricine possesses antiarrhymic and hypotensive actions. Our experimentation demonstrates that dauricine inhidits platelet aggregation induced by the threshold concentration of adenosine diphosphate (ADP), arachidonic acid (AA) and collagen (Coll) in the dose-dependent way in vitro in rabbits. The aggregatipn inhibition rates produced by dauri- cine 0.08 mg/ml for ADP, AA and Coll are 49.20%, 62.26% and 65.75% respectively. The adnimistration of dauricine 10 mg/kg to the rabbits intravenously also inhibits the platelet aggregation induced by the threshold concentration of ADP, AA and Coll, the aggregation inhibition rates being 40.12%, 32.71% and 21.21% respectively. The results show that the action mechanism of dauricine might be related to Ca-antagonism.

The effects of dl-Tetrahydropalmatine ( THP ) on the physiologic properties in the auricle of guinea pig and on isoproterenol and calcium-mediated positive chronotropic action in guinea pig atria were studied.30 minutes after THP 52 nM was added, the contractility was decreased to 53+ ( SD ) 17%(P0.05) in the left auricle of guinea pig. Furthermore, the contractility and automaticity of the right auricle were decreased to 48+13% (P

IHC-65 was found to be a potent inhibitor of platelet function . It inhibited platelet aggregation induced by threshold concentration of ADP, arachidonic acid and collagen with dose-dependent manner in vitro, and at 96?mol/L, AIR ( aggregation inhibition rate,) were 71.56, 66.93 and 68.47% respectively. IHC-65 inhibited platelet serotonin release induced by collagen,and at 96 ?mol/L, release inhibition rate was 82.97%. IHC-65 did not influence cAMP level in platelet significantly. It is concluded that IHC-65 inhibited platelet aggregation and its action mechanism may be related to inhibition of serotonin release and to antagonizing Ca ++ .