Objective: To investigate the regulating effect and mechanism of the cactus fruit polysaccharides (CPFP) for blood pressure in spontaneous hypertension rat (SHR). Method: Fifty male SHR at the age of 15 weeks were randomly divided into SHR model group

CPFP high dosage group (H)

CPFP middle dosage group(M)

CPFP low dosage group (L) and captopril treatment group. Another ten male Wistar rats were served as normal control group. The experimental rats were observed for chang in blood pressure during 24 hours after the first administration. The CPFP were administrated for 9 weeks. The systolic blood pressure(SBP) of experimental rats were observed weekly during nine weeks. The contents of angiotensin I

II (AngI

AngII) and endothelin (ET) were determined by radioimmunoassay respectively

and the plasma renin activity (RA) was calculated according to forming speed of AngI after 9 weeks. Result : After 9 weeks

the SBP level in L

M and H group was depressed obviously with the obvious dose-effect and time-effect relation(P<0.05 or P<0.01). The levels of AngII and ET in H group were significantly lower than that in SHR model group(P<0.05 or P<0.01). Conclusion: CPFP can effectively reduce blood pressure in SHR. Reducing the levels of AngII and ET may be account for CPFP effect on SHR.