ABSTRACT
Institut de Recherches Internationale Servier, 6 Place des Pleides, 92415 Courbevoie, Cedex, France
INTRODUCTION
Endothelial cells synthesise and release vasoactive mediators in response to various neurohumoral substances (e.g. acetylcholine, adenosine trisphosphate, bradykinin, thrombin, etc.) and physical stimuli (e.g. shear stress). Nitric oxide (NO) produced from the L-arginine by endothelial NO synthase and prostacyclin produced from arachidonic acid by cyclooxygenase have been identified as endothelium-derived vasodilators. However, not all endothelium-dependent relaxations can be fully explained by the release of either NO and/or prostacyclin. Another unidentified substance(s) which hyperpolarizes the underlying vascular smooth muscle cells, termed endothelium-derived hyperpolarizing factor (EDHF), may contribute to endothelium-dependent relaxations (for review see Furchgott and Vanhoutte, 1989, Félétou and Vanhoutte, 1996, Mombouli and Vanhoutte, 1997).
