Protective effects of nebivolol and reversal of endothelial dysfunction in diabetes associated with hypertension Adriana Georgescu a, ⁎ , Doina Popov a , Emanuel Dragan a , Elena Dragomir a , Elisabeta Badila b a Institute of Cellular Biology and Pathology “N. Simionescu”, Bucharest, Romania b Emergency Hospital, Bucharest, Romania Received 16 February 2007; received in revised form 5 May 2007; accepted 22 May 2007 Available online 5 June 2007 Abstract This study aims to decipher the potential effects of nebivolol in prevention and/or regression of renal artery dysfunction in diabetes associated with hypertension. Renal arteries were isolated from 80 male mice divided into four experimental groups: (i) group D: diabetics, at 2months since streptozotocin injection; (ii) group Din: mice that at the initiation of streptozotocin diabetes were treated with 10mg/kg b.w./day nebivolol for 2months, to test for the potential prevention of vascular dysfunction; (iii) group Dfin: mice that after 2months of diabetes were treated daily with 10mg/kg b.w./day nebivolol for additional 2months, in order to follow the possible regression of the dysfunction, and (iv) controls (C), age- matched healthy animals. The following measurements were performed: arterial blood pressure, plasma glucose concentration, and the vascular reactivity of the renal arteries in response to noradrenaline (10 - 4 M), acetylcholine (10 - 4 M) and sodium nitroprusside (10 - 4 M). To assess the molecular mechanisms involved in the reactivity of the renal artery, the contribution of mitogen-activated protein kinase (MAP kinase) pathway and of L-type voltage gated Ca 2+ channels (in the contractile response to noradrenaline), of nitric oxide (NO) and Ca 2+ activated K + channels (in the endothelium-dependent vasodilator response), and of cGMP (in the endothelium-independent vasodilator response) was examined by exposing the arteries to corresponding inhibitors, and by using myograph and patch-clamp techniques, immunoblotting and NO assays. Results showed that, group D was characterized by hyperglycemia (blood glucose concentration: 136.66 ± 4.96mg/dl, a value ∼ 65% increased compared to group C) and hypertension (systolic blood pressure: 145.66 ± 5.96mm Hg, a value ∼ 34% increased compared to group C). Compared to group D, group Din was characterized by diminished blood glucose concentration (∼ 1.6 fold), reduced systolic and diastolic blood pressure (∼ 1.3 fold) and heart rate (∼ 1.6 fold), as well as by increased contractile response of the renal artery to noradrenaline (∼ 1.84 fold) and of the impeded vasodilator response to acetylcholine (∼ 1.81 fold) and sodium nitroprusside (∼ 1.42 fold). Together, these effects demonstrate that administration of 10mg/kg b.w./day nebivolol at the moment of diabetes induction has preventive effects, ameliorating diabetes dysfunctions. Compared to group D, group Dfin was characterized by diminished glucose concentration (∼ 1.3 fold), reduced systolic and diastolic blood pressure and heart rate (both ∼ 1.2 fold), and by augmentation of contractile response of the renal artery to noradrenaline (∼ 1.62 fold) and of vasodilator response to acetylcholine (∼ 1.13 fold) and sodium nitroprusside (∼ 1.19 fold). These effects assess that administration of 10mg/kg b.w./day nebivolol after 2months of diabetes contributes to regression of diabetes-associated dysfunctionalies. Nebivolol influenced the molecular mechanisms involved in renal artery reactivity in diabetic and hypertensive mice: it increased the NO production and endothelial NO synthase (eNOS) protein expression, decreased the expression of ∝ protein in L-type calcium channels and Ca 2+ activated K + channels, and diminished the MAP kinase activity. The reported data suggest that nebivolol may offer additional vascular protection for treating diabetes associated with hypertension. © 2007 Elsevier B.V. All rights reserved. Keywords: Renal artery; Nebivolol; Vasodilation; Endothelial dysfunction; Diabetes; Hypertension 1. Introduction Prevention of end-stage renal disease by early detection and treatment is an important tool to stop the growing need for renal replacement therapy. The last decade has brought strong reasons for such an approach. The incidence of end-stage European Journal of Pharmacology 570 (2007) 149 – 158 www.elsevier.com/locate/ejphar ⁎ Corresponding author. Institute of Cellular Biology and Pathology “Nicolae Simionescu”, 8, BP Hasdeu Street, PO Box 35-14, 050568-Bucharest, Romania. Tel.: +40 1 319 4518; fax: +40 1 319 4519. E-mail address: adriana.georgescu@icbp.ro (A. Georgescu). 0014-2999/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.ejphar.2007.05.031