Endothelial alpha-adrenoceptors

Abstract

Vascular endothelial cells release EDRF (endothelium-derived relaxing factor) that functionally antagonizes smooth muscle contraction. EDRF, released at a basal rate or stimulated from α2-adrenoceptors on the endothelium, reduces the maximum contraction and decreases the sensitivity (EC50) of adrenoceptor agonists. The distribution of endothelial α2-adrenoceptors varies between blood vessels and among species. The discovery of these receptors linked with EDRF release adds an important consideration when interpreting the integrated response of the vasculature to catecholamines.