Although hypercholesterolemia is implicated in the patho-physiology of many renal disorders as well as hypertension, its' direct actions in the kidney are not yet clearly understood. In the present study, we evaluated renal responses to administration of cholesterol (8 µg/min/100g BW; bound by polyethylene glycol) into the renal artery of anesthetized male Sprague-Dawley rats. Total renal blood flow (RBF) was measured by a Transonic flow probe and glomerular filtration rate (GFR) was determined by Inulin clearance. In control rats (n=8), cholesterol induced reductions of 10±2 % in RBF (baseline, b, 7.6±0.3 ml/min/g), 17±3 % in urine flow (b, 10.6±0.9 µl/min/g), 29±3 % in sodium excretion (b, 0.96±0.05 µmol/min/g) and 24±2 % in nitrite/nitrate excretion (b, 0.22±0.01 nmol/min/g) without an appreciable change in GFR (b, 0.87±0.03 ml/min/g). These renal vasoconstrictor and anti-natriuretic responses to cholesterol were absent in rats pretreated with nitric oxide (NO) synthase inhibitor, nitro-L-arginine methylester (0.5 µg/min/100g; n=6). In rats pretreated with superoxide (O₂^-) scavenger, tempol (50 µg/min/100g; n=6), the cholesterol induced renal responses remained mostly unchange though there was a slight attenuation in anti-natriuretic response. This anti-natriuretic response to cholesterol was abolished in furosemide pretreated (0.3 µg/min/100g; n=6) but remained unchange in amiloride pretreated (0.2 µg/min/100g; n=5) rats indicating that Na⁺/K⁺/2Cl^- cotransport is the dominant mediator of this effect. These data demonstrate that cholesterol induced acute renal vasoconstrictor and antinatriuretic responses are mediated by a decrease in NO production. These data also indicate that tubular effect of cholesterol on sodium reabsorption is mediated by the furosemide sensitive Na⁺/K⁺/2Cl^- cotransporter.