Objective To explore the anti-hypertensive effect and possible mechanism of Guoteng（ Uncaria Rhynchophylla）. Methods A total of 18 spontaneously hypertensive（ SHR） rats were equally divided into a Guoteng group and a model group

and 9 Wistar rats were selected as the normal group. The rats in the Guoteng group were given 10. 001 g/（ kg·d） of the extracting solution of Guoteng（ Uncaria Rhynchophylla）

and the rats in the model group and the normal group were given 2 ml of normal saline

and were intragastrically administered once a day for 4 weeks. Systolic and diastolic blood pressure were measured in each group after treated 0

1

2

3

and 4 weeks.The changes of urine metabolic markers in each group were analyzed by high performance liquid chromatography with time-of-flight mass spectrometry（ HPLC-TOF/MS） after 4 weeks. Results The systolic and diastolic blood pressures of the model group and the Guoteng group were significantly higher than those of the normal group in 0

1

2

3

and 4 weeks（ P < 0. 01）. Compared with the model group

the systolic blood pressure of the Guoteng group was decreased in 2

3

and 4 weeks（ P < 0. 05）

and the systolic and diastolic blood pressures of the Guoteng group were lower in 4 weeks than those in the 0

1

2 and 3 weeks（ P < 0. 05 or P < 0. 01）. A total of 12 distinctive biomarkers were screened

and analysis showed that the androgen and estrogen metabolism

α-linolenic acid and linoleic acid metabolism

arginine and proline metabolism up-regulation

arachidonic acid metabolism

sphingolipid metabolism

and tryptophan metabolism were down-regulated. Conclusion Guoteng（ Uncaria Rhynchophylla） has a good antihypertensive effect

and an important part of its antihypertensive effect is the regulation of nitric oxide.