Objective: To investigate the effects of ethanol extract of six breeds of Uncaria on blood pressure in normal rat. Method: For acute hypotensive experiment

the rats were randomly divided into normal control group

nifedipine(0.002 g· kg-1) group and ethanol extract groups of six breeds of Uncaria Schreb at dose of crude drug 68.4

34.2 g· kg-1. The common carotid artery blood pressures were recorded 0

0.5

1.0

1.5

2.0

2.5

3.0 hours after single dose administration of medicine to duodenum. For chronic hypotensive experiment

the rats were randomly divided into normal control group

nifedipine(0.002 g· kg-1) group and ethanol extract groups of six breeds of Uncaria Schreb at dose of crude drug 34.2

17.1 g· kg-1. The caudal artery blood pressures were recorded on 0

7

11 days after repeated intragastric administration. Result: Uncaria rhynchophlly(Miq.)Miq.ex Havil at doses of 68.4

34.2 g· kg-1 could significantly decrease the common carotid artery blood pressure of normal rats from 0.5 h to 3 h after single dose administration (P<0.01).U. rhynchophlly(Miq.)Miq.ex Havil at doses of 17.1

34.2 g· kg-1

U. macrophylla Wall and U. rhynchophylloides F.C.How at dose of 34.2 g crude drug· kg-1could significantly decrease the caudal artery blood pressure of normal rats after repeated intragastric administration (P<0.01). But U. scandens (Sm.)Huntch

U. lancifolia Hutch and U. homomalla Miq could not decrease the common carotid artery and caudal artery blood pressure of normal rat. Conclusion: U. rhynchophlly(Miq.)Miq.ex Havil

U. macrophylla Wall and U. rhynchophylloides F.C.How could significantly decrease the blood pressure of normal rats. But U. scandens (Sm.)Huntch

U. lancifolia Hutch and U. homomalla Miq showed no influence on blood pressure in normal rat.