Long-term treatment with nebivolol improves arterial reactivity and reduces ventricular hypertrophy in spontaneously hypertensive rats.

The aim of this study was to assess the effects of long- term nebivolol therapy on high blood pressure, impaired endothelial function in aorta, and damage observed in heart and conductance ar- teries in spontaneously hypertensive rats (SHR). For this purpose, SHR were treated for 9 weeks with nebivolol (8 mg/kg per day). Un- treated SHR and Wistar Kyoto rats were used as hypertensive and normotensive controls, respectively. The left ventricle/body weight ratio was used as an index of cardiac hypertrophy, and to evaluate vascular function, responses induced by potassium chloride, nor- adrenaline, acetylcholine, and sodium nitroprusside were tested on aortic rings. Aortic morphometry and fibrosis were determined in par- allel by a quantitative technique. Systolic blood pressure, measured by the tail-cuff method, was lower in treated SHR than in the un- treated group (194 ± 3 versus 15 0±4m mHg). The cardiac hypertro- phy index was significantly reduced by the treatment. In aortic rings, treatment with nebivolol significantly reduced the maximal response to both KCl and NA in SHR. In vessels precontracted with phenyl- ephrine relaxant, activity due to acetylcholine was higher in normo- tensive rats than in SHR and the treatment significantly improved this response. The effect of sodium nitroprusside on aortic rings was simi- lar in all groups. Medial thickness and collagen content were signifi- cantly reduced in comparison with SHR. In conclusion, the chronic antihypertensive effect of nebivolol in SHR was accompanied by an improvement in vascular structure and function and in the cardiac hypertrophy index.