| Abstrakt: |
The mechanisms for maintenance of renovascular hypertension remain undefined. Excess Angiotensin II generation may lead to release of reactive oxygen species and increased vasoconstrictor activity. The major aim of the present study was to evaluate the effects of acute intravenous (IV) administration of superoxide dismutase mimetic 4-hidroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol) on mean arterial blood pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) in the renovascular hypertension performed in male Wistar rats (6 weeks after renal surgery -- Goldblatt hypertension model -- 2K-1C). Moreover, to examine the oxidative stress in this model, blood samples were collected and measured with thiobarbituric acid-reactive substances (TBARS). Wistar rats were divided in control group (C, n=13) and hypertensive group (2K-1C, n=14). Tempol was infused (10 and 30mg/kg, IV, 6 min.) and MAP, HR and RSNA were monitored for 30 minutes. Acute Tempol treatment (10 mg/kg) in hypertensive rats produced a decrease in MAP (7 ± 1%) during infusion followed by a significant decrease in RSNA (8 ± 2%, p< 0,02), with no changes in HR. Tempol 30mg/kg reduced significantly MAP by 23± 4%, p< 0,001 in 2K-1C and the RSNA decreased 17 ±7%, p<0,04. In normotensives rats, Tempol 10mg/kg didn't change MAP, HR and ANSR. However, in these animals Tempol 30mg/kg produced a reduction in the MAP (10±2%) without modifications in RSNA and HR. The markers of oxidative stress were significantly increased in hypertensive rats (2K-1C: 2,2 ±0,4 vs C 1,6 ±0,3 nmol/ml, p<0,07). In summary, we observed that in renovascular hypertension an increased in MAP and RSNA was associated with increased systemic oxidation. [ABSTRACT FROM AUTHOR] |
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