<qa>  What is the effect of allopurinol on endothelial dysfunction?Recent results from a randomized cross-over study of 30 hyperuricemic, hypertensive adolescents showed that allopurinol 200 mg twice daily resulted in a significant reduction in blood pressure as compared with placebo.4, 15, 16 However, similar studies in adults are lacking and no study has provided insights into mechanisms whereby uric acid might raise blood pressure in humans. Endothelial dysfunction was consistently improved by allopurinol treatment in patients with congestive heart failure17, 18 and several other conditions.19 It would be of great scientific and clinical interest if a mechanistic role for uric acid in adult hypertension could be demonstrated. The investigators have a unique opportunity to examine uric acid as a contributor to overactivity of the intrarenal RAS and impaired nitric oxide production. The investigators hypothesize that hypertensives with elevated uric acid will experience a significant fall in uric acid in response to administration of febuxostat which will correlate with an improvement in vascular responses to infused Ang II, and improved endothelial function. 