Improvement of left ventricular diastolic function induced by ß-blockade: a comparison between nebivolol and metoprolol.

OBJECTIVES: Enhanced adrenergic drive is involved in the development of left ventricular (LV) diastolic dysfunction observed in metabolic syndrome (MS). Thus, ß-blockers might improve LV dysfunction observed in MS, but whether this occurs is unknown. METHODS: We assessed in Zucker fa/fa rats the effects of short- (5 days) and long-term (90 days) metoprolol ('pure' ß-blockade; 80 mg/kg/day) or nebivolol (ß-blocker with vasodilating properties; 5mg/kg/day) treatment on LV hemodynamics and remodeling, as well as the long-term effects on coronary and peripheral endothelial dysfunction. RESULTS: At identical degree of ß(1)-receptor blockade, metoprolol and nebivolol decreased heart rate to the same extent and preserved cardiac output via increased stroke volume. None of the ß-blockers, either after long- or short-term administration, modified LV end-systolic pressure-volume relation. Both ß-blockers reduced, after long-term administration, LV end-diastolic pressure, Tau and end-diastolic pressure-volume relation, and this was associated with reduced LV collagen density, but not heart weight. Similar hemodynamic effects were also observed after short-term nebivolol, but not short-term metoprolol. These short-term effects of nebivolol were abolished by NO synthase inhibition. At the vascular level, nebivolol, and to a lesser extend metoprolol, improved NO dependent coronary vasorelaxation, which was abolished by NO synthase inhibition. CONCLUSIONS: In a model of MS, the ß-blockers metoprolol and nebivolol improve to the same extent LV hemodynamics, remodeling and diastolic function, but nebivolol prevent more markedly endothelium dependent vasorelaxation involving a more marked enhancement of NO bio-availability.