L'endothélium, site de production et de métabolisme des peptides vaso-actifs

Abstract

The vascular endothelium possesses many properties, including production and metabolism of vasoactive peptides. This is a key function for the control of the vascular tone and of the structure of the arterial wall. Three ectoenzymes, belonging to the zinc metallo-peptidases family, are involved : angiotensin I converting enzyme (ACE) that activates angiotensin I into angiotensin II and that degrades bradykinin ; neutral endopeptidase (NEP) that inactivates bradykinin and atrial natriuretic peptide ; endothelin converting enzyme (ECE), that generates endothelin from its inactive precursor, big endothelin. The vascular wall is also probably able to uptake and concentrate some elements of circulating renin-angiotensin system. Endothelial cells synthetize bradykinin and endothelin I that exert a paracrine effect on vascular smooth muscle cells. Therefore, endothelial cells control the production of vasoactive peptides and thereby the local tissular blood flow and the growth of vascular smooth muscle cells. Because of its location between blood and vascular tissues, endothelium is a good target for drugs interfering with the synthesis and (or) the action of vasoactive peptides.