Endothelium-derived contracting factors.

In the past decade, the importance of endothelium in modulating vascular tone has become apparent. Endothelium can produce different vasodilators, such as prostacyclin, endothelium-derived relaxing factor (most likely nitric oxide), and endothelium-derived hyperpolarizing factor. Endothelium can also produce endothelium-derived contracting factors (EDCF) which can induce constriction of the underlying vascular smooth muscle. Constriction may be mediated by a variety of products released by the endothelium. Thus, by responding to various stimuli and releasing either relaxing or contracting factors, the endothelium can set and modulate vascular tone.