| Objective: To study hypotensive effects of extract from Anoectochilus RM2 onrenovascular hypertensive rats (RHR) and its underlying mechanisms.Methods: RHR were produced by two-kidney one clip method. (1) Multimediabiological signal analysis system was used to record systolic blood pressure(SBP),diastolic blood pressure (DBP) and heart rate (HR),by carotid artery intubation beforeand after RM2 was administrated via femoral vein.(2) RHR were given RM2 byintragastric for 15 days, and SBP and HR were measured by tail-cuff method inconsciously were measured on the 5th,10th,15th days after administration RM2.(3) Atthe end of the 15th day, the rats were killed. The plasma concentrations of angiotensinâ…¡( Angâ…¡), endothelin ( ET ) were measured by radioimmunoassay and the serumconcentrations of nitric oxide ( NO ) and nitric-synthase ( NOS ) were tested by nitricacid deoxidized enzyme and biochemistry assay respectively.Results: (1) In acute hypotensive experiments, RM2 markedly reduced SBP ,DBPand decreased HR with a dose-dependent manner. (2) By intragastric administrationof RM2 for 5 days, SBP and HR were significantly reduced. (3) After 15 days by oraladministration, RM2 elevated serum NO, NOS concentrations and lowered plasmaconcentrations ofAng â…¡and ET-1.Conclusions: (1) RM2 lowered SBP, DBP and HR in RHR . (2) The hypotensiveeffects of RM2 on RHR might be involved in increasing the generation of nitric oxideand nitric-synthase and/or decreasing the production of angiotensin â…¡andendothelin in vivo.
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