Effects of sodium nitrite on ischemia-reperfusion injury in the rat kidney.
ABSTRACT Reactive oxygen and nitrogen species play a key role in the pathophysiology of renal ischemia-reperfusion (I/R) injury. Recent studies have shown that nitrite (NO(2)(-)) serves as an endogenous source of nitric oxide (NO), particularly in the presence of hypoxia and acidosis. Nanomolar concentrations of NO(2)(-) reduce injury following I/R in the liver and heart in vivo. The purpose of this study was to evaluate the role of NO(2)(-) in renal I/R injury. Male Sprague-Dawley rats underwent a unilateral nephrectomy followed by 45 min of ischemia of the contralateral kidney or sham surgery under isoflurane anesthesia. Animals received normal saline, sodium NO(2)(-), or sodium nitrate (NO(3)(-); 1.2 nmol/g body wt ip) at 22.5 min after induction of ischemia or 15 min before ischemia. A separate set of animals received saline, NO(2)(-), or NO(3)(-) (0.12, 1.2, or 12 nmol/g body wt iv) 45 min before ischemia. Serum creatinine and blood urea nitrogen were increased following I/R injury but were not significantly different among treatment groups at 24 and 48 h after acute renal injury. Interestingly, NO(3)(-) administration appeared to worsen renal injury. Histological scoring for loss of brush border, tubular necrosis, and red blood cell extravasation showed no significant differences among the treatment groups. The results indicate that, contrary to the protective effects of NO(2)(-) in I/R injury of the liver and heart, NO(2)(-) does not provide protection in renal I/R injury and suggest a unique metabolism of NO(2)(-) in the kidney.
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ABSTRACT: We have been studying the occurrence of low velocity detonations (LVI) in several liquid explosives. A hypothesis based on shock wave interactions and Mach reflections was proposed to explain the initiation and propagation of LVD. Using the card gap test we found general experimental agreement with this hypothesis. However, certain anomalous effects were noted. In addition, we developed a method to study the internal wave structure of a shocked liquid. This technique was applied to a liquid that sustains LVD and to one that does not. A comparison of these liquids shows that the reaction zone in a liquid explosive undergoing LVD is consistent with the Mach zone hypothesis. The anomalous effects noted during gap testing were subjected to a photographic study using a high speed framing camera. The results of this study showed that mechanisms other than that explainable by the Mach zone hypothesis were also responsible for LVD initiation. These were wave reflections from witness plates for high sound speed-high strength confinement and donor air shock initiation for lead (low sound speed-low strength) confinement. We conclude that there appears to be no unique mechanism for LVD and that each mechanism proposed so far explains some of the observations.Symposium (International) on Combustion 01/1969; 12(1):731–742.
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ABSTRACT: Background: In view of the reported efficacy of glucagons-like peptide-1 (GLP-1) on ischemia reperfusion (I/R) injury, this study was designed to assess the effect of exenatide (GLP-1 receptor agonist) on renal I/R in type 2 diabetes mellitus (T2DM). Materials and Methods: T2DM in rats were induced by administration of nicotinamide (230 mg/kg, i.p.), 15 min prior to the single dose of streptozotocin (65 mg/kg, i.v.). In vivo renal I/R were performed in both T2DM and normal rats. Results: The lipid peroxidation, xanthine oxidase activity, and nitric oxide level in renal tissue were significantly increased after I/R in diabetic rats compared to I/R in normal rats. Antioxidant enzymes such as glutathione, superoxide dismutase, catalase, and glutathione peroxidase were significantly reduced after I/R in diabetic rats compared to normal rats. Exenatide treatment significantly normalized these biochemical parameters compared to diabetic I/R rats. Serums TNF-α level and myeloperoxidase activity in renal tissue and apoptosis were also significantly normalized after administration of exenatide. Furthermore, treatment with exenatide (10 mcg/kg) had preserved the normal morphology of the kidney compared to I/R performed in T2DM rats. Conclusion: In conclusion, exenatide protects exaggerated renal I/R injury in T2DM. These findings have major implication in the treatment of ischemic injury that prone to develop in T2DM.International Journal of Diabetes in Developing Countries. 01/2010;
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ABSTRACT: Cl(2) gas toxicity is complex and occurs during and after exposure, leading to acute lung injury (ALI) and reactive airway syndrome (RAS). Moreover, Cl(2) exposure can occur in diverse situations encompassing mass casualty scenarios, highlighting the need for postexposure therapies that are efficacious and amenable to rapid and easy administration. In this study, we assessed the efficacy of a single dose of nitrite (1mg/kg) to decrease ALI when administered to rats via intraperitoneal (ip) or intramuscular (im) injection 30min after Cl(2) exposure. Exposure of rats to Cl(2) gas (400ppm, 30min) significantly increased ALI and caused RAS 6-24h postexposure as indexed by BAL sampling of lung surface protein and polymorphonucleocytes (PMNs) and increased airway resistance and elastance before and after methacholine challenge. Intraperitoneal nitrite decreased Cl(2)-dependent increases in BAL protein but not PMNs. In contrast im nitrite decreased BAL PMN levels without decreasing BAL protein in a xanthine oxidoreductase-dependent manner. Histological evaluation of airways 6h postexposure showed significant bronchial epithelium exfoliation and inflammatory injury in Cl(2)-exposed rats. Both ip and im nitrite improved airway histology compared to Cl(2) gas alone, but more coverage of the airway by cuboidal or columnar epithelium was observed with im compared to ip nitrite. Airways were rendered more sensitive to methacholine-induced resistance and elastance after Cl(2) gas exposure. Interestingly, im nitrite, but not ip nitrite, significantly decreased airway sensitivity to methacholine challenge. Further evaluation and comparison of im and ip therapy showed a twofold increase in circulating nitrite levels with the former, which was associated with reversal of post-Cl(2) exposure-dependent increases in circulating leukocytes. Halving the im nitrite dose resulted in no effect in PMN accumulation but significant reduction of BAL protein levels, indicating a distinct nitrite dose dependence for inhibition of Cl(2)-dependent lung permeability and inflammation. These data highlight the potential for nitrite as a postexposure therapeutic for Cl(2) gas-induced lung injury and also suggest that administration modality is a key consideration in nitrite therapeutics.Free Radical Biology and Medicine 08/2012; 53(7):1431-9. · 5.27 Impact Factor