2. To determine the effects of fenoldopam mesylate alone or in combination with MESNA on reperfusion injury as evidenced by changes in the level of urinary 15-F2t-isoprostanes The rational is that failure of parenteral vasodilators to reduce the incidence of death or dialysis among patients with ATN may involve the extension of tubular injury through normalization of renal blood flow and subsequent reperfusion injury. Moreover, the generation of reactive oxidative species in areas of hypoxia could blunt impair regional blood flow in the kidney through inhibition of nitric oxide production.