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We investigated the role of renal perfusion pressure (RPP) on renal scavenging pathways of reactive oxygen species (ROS) in Sprague Dawley rats. Rats were prepared with carotid and femoral arterial catheters, a femoral venous catheter, and a servo-controlled aortic balloon occluder positioned between the renal arteries. Rats were infused with either Ang II (5 ng/kg/min) + L-NAME (1.4 ug/kg/min) or saline. At 3, 7, and 14 days of infusion, both kidneys were removed and the cortex (CX) and outer medulla (OM) separated. Enzyme activities for catalase (CAT) and superoxide dismutase (SOD) were measured at each time point as were protein expression levels of CAT, SOD1 (Cu/Zn), and SOD2 (Mn). RPP in uncontrolled kidneys of Ang 11 + L-NAME rats was significantly increased versus servo-controlled kidneys (p < 0.05) at 3 (143 ± 1 vs. 116 ± 1 mmHg), 7 (153 ± 2 vs. 117 ± 1 mmHg), and 14 (151 ± 1 vs. 113 ± 1 mmHg)days of infusion. CAT and SOD activities and expression were similar in both servo-controlled and uncontrolled kidneys compared to those of saline-infused rats. Interestingly, in the CX vs. OM, CAT and SOD activity were significantly higher (p < 0.05) at 3 (5x and 2x, respectively), 7 (5x and 2x), and 14 (7x and 2x) days. We conclude that pressure per se does not affect CAT or SOD activity and expression during Ang II + L-NAME hypertension. Lower ROS scavenging activity in the OM versus CX may predispose the OM to injury in hypertension. [ABSTRACT FROM AUTHOR]