Abstract: AIM: To study the effect of nevilolol on circle and aortic renin-angiotensin system (RAS) in spontaneously hypertensive rats (SHR).METHODS: SHR and age-matched Wistar-Kyoto (WKY) rats were randomly divided into 4 groups: (1) Nebivolol group(n=6): SHR were treated with nebivolol(5 mg·kg^-1·d^-1, i.g.); (2) Captopril group (n=6): SHR were treated with captopril (15 mg·kg^-1·d^-1, i.g.); (3) SHR control group (n=6): SHR were treated with vehicle once daily, i.g.; (4) WKY control group (n=6): WKY were treated with vehicle once daily, i.g. The therapy was continued for 8 weeks. At the end of this study, animals were anesthetized with 3% sodium pentobarbital (30 mg/kg, i.p.). Plasma renin activity (PRA) was measured. Plasma and aortic nitric oxide (NO), angiotensin Ⅱ(AngⅡ), NO/AngⅡ and angiotnesin converting enzyme(ACE ) activity were also measured.RESULTS: Compared with WKY, the levels of NO, NO/AngⅡin plasma and aortic were lowered, while the level of AngⅡ was increased in SHR. ACE activity in aorta form SHR were increased than those in WKY, but plasma ACE activity was reduced. There was no difference in PRA between SHR and WKY. Nebivolol did not affect plasma AngⅡand ACE activity. But nebivolol reduced aortic AngⅡ concentration and inhibited aortic ACE activity. Nebivolol could increase the levels of plasma and aortic NO and NO/AngⅡ in SHR.CONCLUSION: The antihypertensive effect of nebivolol in SHR is accompanied by the inhibition of RAS.

Key words: Nebivolol, Renin-angiotensin system, Spontaneously hypertensive rats