Vasodilators and Anti-Oxidant Therapy in Early ATN

Primary Hypotheses: * Combination therapy with intravenous fenoldopam mesylate and MESNA will reduce the incidence of dialysis and all cause mortality at 21 days in patients with established acute tubular necrosis (ATN). * The combination of fenoldopam mesylate and Intravenous MESNA reduces the level of reactive oxygen species released following restoration of renal blood flow in patients with ischemic ATN. Specific Aims 1. To conduct a multicenter, double blind, trial comparing the efficacy of a 72-hour infusion of fenoldopam mesylate or combination of fenoldopam plus intravenous MESNA to reduce the incidence of dialysis or all-cause mortality at 21 days in patients with ischemic ATN. 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. 3. To serially measure the urinary content of ICAM-1, VCAM-1, KIM-1, P-selectin, E-selectin, MCP-1and Cyr-61 and determine the ability of specific markers to identify patients progressing to dialysis dependent ATN. The rational is that ICAM-1 is expressed by ischemic endothelium and facilitates neutrophile migration into areas of necrotic epithelium. We will determine whether rising urinary ICAM-1 will identify patients with progressive dialysis-dependent ATN. Specific aim #3 will also examine whether a reduction in dialysis or all cause mortality by fenoldopam mesylate correlates with reduced urinary expression of ICAM-1 or other cell adhesion molecules. The serum, plasma, urine supernatant and urinary casts obtained from patients enrolled in this trial will be made available to other investigators involved in the study of early ATN.