title: Superoxide anion is involved in the breakdown of endothelium-derived vascular relaxing factor.
abstract: Endothelium-derived vascular relaxing factor (EDRF) is a humoral agent that is released by vascular endothelium and mediates vasodilator responses induced by various substances including acetylcholine and bradykinin. EDRF is very unstable, with a half-life of between 6 and 50 s, and is clearly distinguishable from prostacyclin. The chemical structure of EDRF is unknown but it has been suggested that it is either a hydroperoxy- or free radical-derivative of arachidonic acid or an unstable aldehyde, ketone or lactone. We have examined the role of superoxide anion (O-2) in the inactivation of EDRF released from vascular endothelial cells cultured on microcarrier beads and bioassayed using a cascade of superfused aortic smooth muscle strips. With this system, we have now demonstrated that EDRF is protected from breakdown by superoxide dismutase (SOD) and Cu2+, but not by catalase, and is inactivated by Fe2+. These findings indicate that O-2 contributes significantly to the instability of EDRF.
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism; D003300:Copper / Q000378:metabolism; D004727:Endothelium / Q000502:physiology*; D007501:Iron / Q000378:metabolism; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009569:Nitric Oxide; D011817:Rabbits; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000502:physiology*; D014665:Vasodilator Agents / Q000378:metabolism*
chemical_list: D014665:Vasodilator Agents; D013481:Superoxides; D009569:Nitric Oxide; D003300:Copper; D007501:Iron; D002374:Catalase; D013482:Superoxide Dismutase; D001920:Bradykinin