Role of the endothelium in controlling local blood flow

During this last decade it has been widely recognized that the vascular endothelium reacts to mechanical force as well as to various neurohumoral mediators by releasing vasodilator and/or vasoconstrictor substances, and thus contributes to the relaxation of local blood vessels and the control of local circulation. In addition, substances produced and released by endothelial cells play a major role in controlling platelet-endothelium interaction and platelet aggregation. The endothelium may contribute to the local control of vascular tone by secreting prostacyclin, endothelium-derived relaxing factor(s) (EDRF) or endothelium derived contracting factor(s) (EDCF). Prostacyclin, a major metabolite of the cyclo-oxygenase pathway in the vascular endothelium and the subject of intense studies since its discovery in 1976, has been reviewed many times and will therefore not be discussed in this report. We will focus on other recently described endothelium-dependent vasoactive mediators, particularly EDRF and EDCF.