Kidney damage after renal ablation is worsened in endothelial nitric oxide synthase -/- mice and improved by combined administration of L-arginine and antioxidants.

AIM: Reduction in nitric oxide (NO) levels during kidney failure has been related to the reaction of NO with superoxide anions to yield peroxynitrite which possesses the biological activity responsible for renal damage. However, stimulation of the NO pathway ameliorates the progression of kidney failure. Thus, it is unclear whether NO prevents or acts as the compound responsible for the cytotoxicity observed during kidney failure. METHODS: We evaluated the development of kidney failure in animals that were wild type and deficient in endothelial NO synthase (eNOS -/-) and tested the effects of an antioxidant treatment and NO precursors on the generation of superoxide anion and kidney failure parameters. RESULTS: In wild-type mice, five-sixths nephrectomy increased proteinuria from 3.0 +/- 0.35 to 14.5 +/- 0.76 mg protein/24 h (P < 0.05), blood pressure from 83.1 +/- 1.8 to 126.6 +/- 1.7 mmHg (P < 0.05), and superoxide production from 1.4 +/- 0.6% to 74.3 +/- 0.8% (P < 0.05). The effects of five-sixths nephrectomy on the eNOS -/- mice were greater compared with wild-type mice. Proteinuria increased from 6.7 +/- 0.5 to 22.7 +/- 2.0 mg protein/24 h (P < 0.05), blood pressure increased from 93.3 +/- 0.9 to 151.2 +/- 3.4 mmHg (P < 0.05), and superoxide production increased from 12.9 +/- 0.5% to 99.8 +/- 1.3% (P < 0.05). The nitrotyrosine levels were lower in eNOS -/- mice as compared to wild-type mice. A combination of L-arginine and antioxidant treatment ameliorated renal damage. The effect was improved in wild-type animals. CONCLUSION: Our data support the relevance of NO as an antagonist to superoxide in renal tissues and suggest that the loss of this mechanism promotes the progression of kidney failure.

Lead exposure effect on angiotensin II renal vasoconstriction.

Low levels of chronic lead exposure can produce hypertension and endothelial dysfunction, which could be associated with oxidative stress, changes in vascular tone and an imbalance of endothelial-derived vasoconstriction and vasodilator factors. The aim was to investigate the effect of chronic lead-exposure on angiotensin II-induced vasoconstriction in isolated perfused kidney and microvessels. Male Wistar rats (230-250 g) were treated for 12 weeks with lead acetate (100 ppm, Pbgroup) or pure water (control group). We evaluated the vascular reactivity in the kidneys and renal microvessels in the presence and absence of N(omega)-nitro-L-arginine methyl ester (L-NAME) in both groups. The nitrite concentration in renal perfusate was measured as an index of NO released, renal abundance of 3-nitrotyrosine was measured as well as endothelial NO synthase (eNOS) expression. Oxidative stress was measured by using the oxidative fluorescence dye dihydroethidium (DHE) to evaluate in situ production of superoxide and identified by confocal microscopy. Lead-exposure significantly increased blood pressure, eNOS protein expression, oxidative stress and vascular reactivity to angiotensin II. L-NAME potentiated vascular response to angiotensin II in control group but had no effect on the Pb-group. Nitrites released from the kidney of lead-group was lower compared to the control group while 3-nitrotyrosine was higher. This data suggest that lead-induced hypertension could be caused partially by an altered NOsystem.

Nitric oxide-dependent neovascularization role in the lower extremity disease.

Peripheral arterial occlusive disease (PAD) describes vascular disorders associated with ischemia and PAD affects about 8 million people in the United States. Moreover, PAD's prevalence can increase dramatically if cardiovascular disease is present. In healthy individuals reducing blood flow through the lower extremity is followed by a physiological process to limit ischemia in the distal tissue. This process is called revascularization and impairing revascularization results in PAD. Studies suggest nitric oxide (NO) maybe involved in the ischemia-dependent hindlimb revascularization process. NO is increased in the ischemic hindlimb and eliminating NO impairs the revascularization process. Moreover, restoring NO improves hindlimb revascularization. NO may be acting through its effects on vascular tone, cell migration, or extracellular matrix degradation. The present review illustrates nitric oxide's critical role in the ischemia-induced hindlimb revascularization. Thus, restoring normal NO levels in diseased arteries may represent a viable therapeutic avenue by supplementing exogenous NO or employing therapeutic strategies to either increase NO synthesis and its messengers or decrease NO catabolism.