Nitric Oxide Contributes to Vasomotor Tone in Hypertensive African Americans Treated With Nebivolol and Metoprolol.
Endothelial dysfunction is more prevalent in African Americans (AAs) compared with whites. The authors hypothesized that nebivolol, a selective β1 -antagonist that stimulates nitric oxide (NO), will improve endothelial function in AAs with hypertension when compared with metoprolol. In a double-blind, randomized, crossover study, 19 AA hypertensive patients were randomized to a 12-week treatment period with either nebivolol 10 mg or metoprolol succinate 100 mg daily. Forearm blood flow (FBF) was measured using plethysmography at rest and after intra-arterial infusion of acetylcholine and sodium nitroprusside to estimate endothelium-dependent and independent vasodilation, respectively. Physiologic vasodilation was assessed during hand-grip exercise. Measurements were repeated after NO blockade with L-N(G) -monomethylarginine (L-NMMA) and after inhibition of endothelium-derived hyperpolarizing factor (EDHF) with tetraethylammonium chloride (TEA). NO blockade with L-NMMA produced a trend toward greater vasoconstriction during nebivolol compared with metoprolol treatment (21% vs 12% reduction in FBF, P=.06, respectively). This difference was more significant after combined administration of L-NMMA and TEA (P<.001). Similarly, there was a contribution of NO to exercise-induced vasodilation during nebivolol but not during metoprolol treatment. There were significantly greater contributions of NO and EDHF to resting vasodilator tone and of NO to exercise-induced vasodilation with nebivolol compared with metoprolol in AAs with hypertension.
Division of Cardiology, Emory University School of Medicine, Atlanta, GA.
Robert B
RB
Neuman
Division of Cardiology, Emory University School of Medicine, Atlanta, GA.
Salim S
http://orcid.org/0000-0003-0180-349X
SS
Hayek
Division of Cardiology, Emory University School of Medicine, Atlanta, GA.
Joseph C
JC
Poole
Division of Cardiology, Emory University School of Medicine, Atlanta, GA.
Ayaz
A
Rahman
Division of Cardiology, Emory University School of Medicine, Atlanta, GA.
Vivek
V
Menon
Division of Cardiology, Emory University School of Medicine, Atlanta, GA.
Nino
N
Kavtaradze
Department of Pharmacology, Louisiana State University Health Sciences Center, New Orleans, LA.
David
D
Polhemus
Division of Cardiology, Emory University School of Medicine, Atlanta, GA.
Emir
E
Veledar
Department of Pharmacology, Louisiana State University Health Sciences Center, New Orleans, LA.
David J
DJ
Lefer
Division of Cardiology, Emory University School of Medicine, Atlanta, GA.
Arshed A
AA
Quyyumi
D001741:Black or African American; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005542:Forearm / Q000098:blood supply; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000208:ethnology / Q000378:metabolism* / Q000473:pathology; D008790:Metoprolol / Q000008:administration & dosage*; D009123:Muscle Hypotonia; D000068577:Nebivolol / Q000008:administration & dosage*; D009569:Nitric Oxide / Q000378:metabolism*; D010991:Plethysmography; D012039:Regional Blood Flow / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*; D014666:Vasomotor System / Q000378:metabolism* / Q000473:pathology
D000068577:Nebivolol; D009569:Nitric Oxide; D008790:Metoprolol