NO is involved in the sympathetic regulation of vascular tone and in the control of endothelium homeostasis. The main mechanism leading to increased eNOS activity in endothelial cells is calcium-dependent, but phosphorylation at several loci of the NOS proteins has been recognized as an additional pathway to induce both activation and inhibition of eNOS activity. NO diffuses to vascular smooth muscle and produces relaxation by stimulating sGC to increase the levels of the second messenger cGMP. Vascular endothelial cells might also express β-adrenoceptors, thus supporting the hypothesis that the endothelium might control or facilitate β-adrenergic effects on the vessels. Acute β-adrenergic activation caused by β-adrenoceptor agonists stimulates eNOS activity and could increase release of endothelial NO. Permanently high catecholamine levels could lead to overactivation of β-adrenoceptors, increasing eNOS activity and expression. This condition may lead to the uncoupling of eNOS, which produces O₂₋ and ONOO⁻ (ROS). An unbalanced production of NO and O₂₋ is responsible for the formation of ONOO⁻, thus provoking vascular dysfunction. Several stimuli, such as oscillatory shear stress, hyperglycemia and lipid peroxidation could cause impairment in the NADPH oxidase system that, in turn, produces accumulation of ROS and reduction of NO content. Nebivolol, a β-blocker with a distinctive profile, combines the properties of a β₁-AR antagonist and β₃-AR agonist. Nebivolol could enhance NO release via stimulation of β₃-ARs and, thanks to its antioxidant activity, it prevents the detrimental effect on NO bioavailability associated to oxidative stress. Life-style changes and non-pharmacological interventions (such as caloric restriction and exercise training) show a positive role on the maintenance of cardiovascular homeostasis, at least in part, by inducing the activation of eNOS and increasing NO bioavailability. Abbreviations: AR, adrenoreceptor; cGMP, cyclic guanosine monophosphate; eNOS, endothelial nitric oxide synthase; GTP, guanosine 5′-triphosphate; NADPH, reduced nicotinamide adenine dinucleotide phosphate; NO, nitric oxide; O⁻₂, superoxide; ONOO⁻, peroxynitrite; P, phosphoryl; ROS, reactive oxygen species; sGC, soluble guanylate cyclase. ↓ Activation; ⊥ inhibition.