In patients with coronary disease, the treatment with the angiotensin receptor blocker losartan reduced the endothelium-bound XOR activity and XOR inhibition with oxypurinol improved endothelium-dependent vasodilation, suggesting that endothelial dysfunction in coronary disease is at least in part dependent on angiotensin II-dependent endothelial XOR activation [40]. Here, XDH is linked to endothelial dysfunction.