['Impaired endothelium-dependent vasodilation represents an early manifestation of atherosclerosis. Prospective studies have demonstrated that impaired endothelial function in the peripheral circulation of hypercholesterolemic patients predicts CV events and can be restored by statin treatment. Whether this also holds true in the renal circulation has not yet been adequately addressed.', 'In a double-blind, randomized, placebo-controlled cross-over trial, 40 hypercholesterolemic patients were randomly assigned to receive rosuvastatin (10mg/day) and matching placebo. The primary objective of the study was to assess the effect of 6-week treatment with rosuvastatin on basal NOS activity of the renal vasculature, as assessed by measuring renal plasma flow (RPF) both before and after blockade of NOS with systemic infusion of N(G)-monomethyl-L-arginine (L-NMMA). In a subgroup of 20 patients we also studied the effects of a 3-day treatment regimen.', 'Compared to placebo treatment, rosuvastatin decreased LDL-cholesterol levels both after 3 days and 6 weeks of treatment. The decrease in RPF in response to L-NMMA was significantly more pronounced after 6-week therapy with rosuvastatin compared to placebo (-13.7+/-1.0% versus -11.3+/-0.7%; p=0.046), indicating increased basal NOS activity with rosuvastatin treatment. A trend towards improved basal NOS activity was already evident after 3-day treatment.'] Does rosuvastatin improve basal nitric oxide activity of the renal vasculature in patients with hypercholesterolemia?