[Role of the L-arginine/nitric oxide system in the action of nebivolol].

Beta-blockers exert their effects through blockade of beta-adrenoceptors. First-generation beta-blockers non-selectively block beta1- and beta2-adrenoceptors, while second-generation beta-blockers predominantly block beta1-adrenoceptors. Third-generation beta-blockers possess additional vasodilator properties. Nebivolol is a highly selective b1-blocker with additional vasodilator effects which are mediated by the endothelial L-arginine/nitric oxide system. The hemodynamic action of nebivolol differs from those of first and second-generation beta-blockers: it acutely decreases peripheral resistance (while first and second-generation beta-blockers cause an initial transient increase in peripheral resistance) and decreases in heart rate that are less pronounced than those evoked by first and second-generation beta-blockers. Beta-blockers are frequently used in the treatment of hypertension, coronary artery disease and chronic heart failure. Nebivolol should thus be a suitable drug for treating these diseases, especially since nitric oxide has vasodilator and anti-atherogenic effects. One long-term trial (the SENIORS study) has shown that nebivolol, compared with a placebo, reduced death and hospital admission in elderly patients with chronic heart failure. Additional studies are needed to investigate the clinical relevance of nitric oxide-mediated vasodilatation and to show if nebivolol is as efficacious as the other beta-blockers--metoprolol, bisoprolol and carvedilol--in the treatment of chronic heart failure.