Chronic Iron Administration Increases Vascular Oxidative Stress and Accelerates Arterial Thrombosis

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Abstract
Background— Iron overload has been implicated in the pathogenesis of ischemic cardiovascular events. However, the effects of iron excess on vascular function and the thrombotic response to vascular injury are not well understood. Methods and Results— We examined the effects of chronic iron dextran administration (15 mg over 6 weeks) on thrombosis, systemic and vascular oxidative stress, and endothelium-dependent vascular reactivity in mice. Thrombus generation after photochemical carotid artery injury was accelerated in iron-loaded mice (mean time to occlusive thrombosis, 20.4±8.5 minutes; n=10) compared with control mice (54.5±35.5 minutes, n=10, P=0.009). Iron loading had no effect on plasma clotting, vessel wall tissue factor activity, or ADP-induced platelet aggregation. Acute administration of dl-cysteine, a reactive oxygen species scavenger, completely abrogated the effects of iron loading on thrombus formation, suggesting that iron accelerated thrombosis through a pro-oxidant mechanism. Iron loadin...