Comparative effect of atenolol and nebivolol on reverse remodeling of intramural coronary arterioles in the spontaneously hypertensive rat model

Objective: Arterial hypertension is an established major risk factor for ischemic heart disease. Functional and structural abnormalities at the level of the microcirculation may play a crucial role in coronary microvascular dysfunction. Indeed, coronary flow reserve is often reduced at angiography in hypertensive patients independently on the presence of left ventricular hypertrophy (Mancini M. et al. Microcirculation 2017). The aim of this study was to assess the effect of the beta-blocker Atenolol and the selective third-generation beta1-adrenergic antagonist Nebivolol on markers of remodeling and endothelial dysfunction in coronary microvascular. Nebivolol has been demonstrated to possess direct vasodilator and antioxidant properties which may improve endothelial dysfunction and reduce smooth muscle cell proliferation. Design and method: For this purpose, we used three groups of SHR rats: Hypertensive untreated group (SHR); SHR plus Atenolol 50 mg/kg/day by oral gavaging for 8 weeks (SHR + ATE); SHR plus Nebivolol 20 mg/kg/day by oral gavaging for 8 weeks (SHR + NEB). Protein expression levels of vasoactive factors, oxidative stress and remodeling markers in coronary microcirculation were determined by immunohistochemical analysis of Endothelin-1 (ET-1), inducible nitric oxide synthase (iNOS) and transforming growth factor-beta1 (TGF-beta1). Results: No differences were observed in structural parameters of mesenteric arteries among groups. SHR + NEB showed a significant reduction in ET-1, iNOS, and TGF-beta1 staining in coronary small arteries comparing to SHR and SHR + ATE. Conclusions: In comparison to atenolol, nebivolol may provide additional benefit beyond blood pressure reduction and beta-receptor blockade since show greater activity in the modulation of protein involved in vasodilation and oxidative stress protection.