[Endothelium-derived hyperpolarizing factor]

Endothelial cells control the tone of the underlying smooth muscle by releasing relaxing factors, such as nitric oxide (NO), prostacycline, endothelium-derived hyperpolarizing factor (EDHF) and contracting factors such as thromboxane A2, endothelins, endoperoxides and superoxide anion. The term EDHF should be restricted to a relaxing factor(s) that differs from NO and prostacyclin. The nature of EDHF is as yet unknown. EDHF might be a cytochrome P-450 metabolite of arachidonic acid or an endogenous cannabinoid--anandamide. The EDHF component of the relaxation is more important in smaller than larger arteries. In various models of disease and in aging animals endothelium-dependent hyperpolarization is diminished. The identification of EDHF and the understanding of its physiological role could lead to the design of new therapies în several cardiovascular diseases.