[Endothelial function in coronary atherosclerosis and heart failure--the role of nitric oxide in regulation of vasomotor tone].

The endothelium plays a pivotal role in synthesizing biologically active substances that modulate the vascular tone of underlying smooth muscle cells. Assessment of endothelial function requires measurement of the effects of endothelium-dependent and -independent vasodilators on the systemic microcirculation or resistance vessels. Endothelial dysfunction has been demonstrated early in the course of coronary artery disease, both by studying vasomotor responses in coronary and peripheral vessels, and in the peripheral circulation of patients with chronic heart failure. The impairment of endothelium-dependent vasodilation is related to an abnormality in the endothelium-derived nitric oxide system. The evolving understanding of the complex and probably multifactorial underlying molecular mechanisms of endothelial dysfunction has lead to the identification of potential beneficial therapeutic interventions. Restoration of endothelial function has been associated with fewer episodes of ischaemia in coronary artery disease and improved exercise capacity in heart failure. In light of recent studies we discuss the role of the endothelium, with special emphasis on nitric oxide, in the regulation of vascular tone in coronary artery disease and heart failure.