Hypoxia and Inflammatory Injury in Human Renovascular Hypertension

Inclusion Criteria: * Creatinine \<2.2 mg/dL for Caucasian males, \<2.0 Caucasian females,\< 2.4 African-American males, \<2.1 mg/dL African-American females * Hypertension (Systolic BP\>155 mm Hg) and/or requirement for two or more antihypertensive medications: no restrictions on antihypertensive agents, although loop diuretics will be changed to diluting site agents (e.g. hydrochlorothiazide, indapamide, metolazone) prior to study. * Angiotensin Converting Enzyme (ACE inhibitor) or Angiotensin Receptor Blocker (ARB) therapy maintained or initiated at usual recommended daily dose (equivalent: 40 mg lisinopril) . Exclusion Criteria: * Diabetes requiring insulin or oral hypoglycemic medications (see text) * Known allergy to furosemide or iodinated intravenous contrast * Pregnancy * Recent Cardiovascular event: Myocardial infarction, stroke, congestive heart failure within 3 months * Cardiac ejection fraction less than 30% * Evidence of hepatitis B or C, or HIV infection * requirement for potentially nephrotoxic drugs, e.g. non-steroidal anti-inflammatory drugs * Uncontrolled hypertension: SBP \>180 mm Hg, despite antihypertensive therapy * Kidney transplant * Pacemaker, implantable defibrillator or other contraindication to Magnetic resonance imaging * Inability to comply with breath-hold for 30 seconds * History of deep venous thrombosis within 3 months of enrollment * contraindications to renal biopsy including artificial valve requiring continuous anticoagulation