3-nitrotyrosine and Necrosis

Exposure to fine particulate air pollution (PM₂.₅) is strongly associated with cardiovascular morbidity and mortality. Exposure to PM₂.₅ during pregnancy promotes reduced birthweight, and the associated adverse intrauterine conditions may also promote adult risk of cardiovascular disease. Here, we investigated the potential for in utero exposure to diesel exhaust (DE) air pollution, a major source of urban PM₂.₅, to promote adverse intrauterine conditions and influence adult susceptibility to disease. We exposed pregnant female C57Bl/6J mice to DE (≈300 µg/m³ PM₂.₅, 6 hrs/day, 5 days/week) from embryonic day (E) 0.5 to 17.5. At E17.5 embryos were collected for gravimetric analysis and assessed for evidence of resorption. Placental tissues underwent pathological examination to assess the extent of injury, inflammatory cell infiltration, and oxidative stress. In addition, some dams that were exposed to DE were allowed to give birth to pups and raise offspring in filtered air (FA) conditions. At 10-weeks of age, body weight and blood pressure were measured. At 12-weeks of age, cardiac function was assessed by echocardiography. Susceptibility to pressure overload-induced heart failure was then determined after transverse aortic constriction surgery. We found that in utero exposure to DE increases embryo resorption, and promotes placental hemorrhage, focal necrosis, compaction of labyrinth vascular spaces, inflammatory cell infiltration and oxidative stress. In addition, we observed that in utero DE exposure increased body weight, but counterintuitively reduced blood pressure without any changes in baseline cardiac function in adult male mice. Importantly, we observed these mice to have increased susceptibility to pressure-overload induced heart failure, suggesting this in utero exposure to DE 'reprograms' the heart to a heightened susceptibility to failure. These observations provide important data to suggest that developmental exposure to air pollution may strongly influence adult susceptibility to cardiovascular disease.

Topics: Air Pollutants; Animals; Aorta; Blood Pressure; Echocardiography; Female; Heart Failure; Inflammation; Inhalation Exposure; Leukocyte Common Antigens; Male; Maternal Exposure; Mice; Mice, Inbred C57BL; Myocardium; Necrosis; Oxidative Stress; Particle Size; Pregnancy; Pregnancy, Animal; Time Factors; Tyrosine; Vehicle Emissions; Weight Gain

The aim of the study was to investigate the ameliorative effects and the mechanism of action of L-2-oxothiazolidine-4-carboxylate (OTC) on acetaminophen (APAP)-induced hepatotoxicity in mice. Mice were randomly divided into six groups: normal control group, APAP only treated group, APAP + 25 mg/kg OTC, APAP + 50 mg/kg OTC, APAP + 100 mg/kg OTC, and APAP + 100 mg/kg N-acetylcysteine (NAC) as a reference control group. OTC treatment significantly reduced serum alanine aminotransferase and aspartate aminotransferase levels in a dose dependent manner. OTC treatment was markedly increased glutathione (GSH) production and glutathione peroxidase (GSH-px) activity in a dose dependent manner. The contents of malondialdehyde and 4-hydroxynonenal in liver tissues were significantly decreased by administration of OTC and the inhibitory effect of OTC was similar to that of NAC. Moreover, OTC treatment on APAP-induced hepatotoxicity significantly reduced the formation of nitrotyrosin and terminal deoxynucleotidyl transferase dUTP nick end labeling positive areas of liver tissues in a dose dependent manner. Furthermore, the activity of caspase-3 in liver tissues was reduced by administration of OTC in a dose dependent manner. The ameliorative effects of OTC on APAP-induced liver damage in mice was similar to that of NAC. These results suggest that OTC has ameliorative effects on APAP-induced hepatotoxicity in mice through anti-oxidative stress and anti-apoptotic processes.

Topics: Acetaminophen; Alanine Transaminase; Aldehydes; Analgesics, Non-Narcotic; Animals; Antioxidants; Apoptosis; Aspartate Aminotransferases; Caspase 3; Chemical and Drug Induced Liver Injury; DNA Fragmentation; Glutathione; Glutathione Peroxidase; Liver; Male; Malondialdehyde; Mice; Mice, Inbred BALB C; Necrosis; Oxidative Stress; Pyrrolidonecarboxylic Acid; Thiazolidines; Tyrosine

Diethylnitrosamine (DEN) treatment increases the generation of reactive oxygen species (ROS), apoptosis, necrosis and proliferation in the liver. Blueberries (BB; Vaccinium corymbosum L.) contain polyphenols and other active components and have high antioxidant capacities. We investigated the effect of BB pretreatment on DEN-induced liver injury and oxidative and nitrosative stress in male rats. Rats were fed with 5% and 10% BB containing diet for six weeks and DEN (200mg/kg; i.p.) was applied two days before the end of this period. Liver function tests were determined in serum and histopathological evaluation was performed in the liver tissue. Apoptosis-related proteins, Bax and B cell lymphoma-2 (Bcl-2) and proliferating cell nuclear antigen (PCNA) expressions were also examined. Oxidative and nitrosative stress were evaluated in the liver by measuring thiobarbituric acid reactive substances, diene conjugate, protein carbonyl and nitrotyrosine levels, and glutathione levels and glutathione peroxidase, superoxide dismutase and glutathione transferase (GST) activities. Pretreatment with high dose of BB reduced apoptotic, necrotic and proliferative changes in the liver induced by DEN. Dietary BB also decreased hepatic lipid peroxidation, protein oxidation and nitrotyrosine levels together with increased GST activity. In conclusion, BB may have an inhibiting effect on acute liver injury by reducing apoptosis, necrosis, proliferation, oxidative and nitrosative stress in DEN-treated rats.

Topics: Animals; Antioxidants; Apoptosis; Biomarkers; Blueberry Plants; Cell Proliferation; Chemical and Drug Induced Liver Injury; Diethylnitrosamine; Disease Models, Animal; Drug Administration Schedule; Fruit; Glutathione; Glutathione Peroxidase; Glutathione Transferase; Liver; Male; Necrosis; Oxidative Stress; Phytotherapy; Plant Extracts; Plants, Medicinal; Protein Carbonylation; Rats; Rats, Wistar; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances; Time Factors; Tyrosine

To investigate whether "binge" and escalating alcohol exposure in the rat influences the development of pathological liver injury.. Time courses for the formation of eicosanoids by cyclooxygenase (COX), oxidative stress and nitrosative stress production, expression of hypoxia-inducible factor 1 (HIF-1), cytokines, hepatic tissue necroinflammation, and fibrosis were assessed in rats during 16 weeks of daily alcohol gavage.. In this model of binge and escalating levels of alcohol, hepatic steatosis, necrosis, and inflammation as well as fibrosis were increased over the 16-week period. The levels of COX-2, oxidative stress, nitrosative stress, HIF-1, proinflammatory mediators (tumor necrosis factor-α, interleukin 1(β) [IL-1(β) ], IL-6), and procollagen-I were increased over the 16-week period. The content of IL-10 in rat serum increased at the end of 4 and 8 weeks but decreased thereafter and was significantly decreased at 12 and 16 weeks.. A rat model of alcoholic liver disease (ALD) with long-term binge and escalating ethanol exposure was developed. Our data support the hypothesis that enhanced eicosanoid production by COX, oxidative stress and nitrosative stress, HIF-1, and the imbalance between pro- and anti-inflammatory cytokines plays an important role in the pathogenesis of ALD.

Topics: Animals; Binge Drinking; Cyclooxygenase 1; Cyclooxygenase 2; Cytokines; Ethanol; Hypoxia-Inducible Factor 1; Inflammation; Inflammation Mediators; Liver; Liver Cirrhosis; Male; Necrosis; Nitric Oxide Synthase Type II; Oxidative Stress; Procollagen; Rats; Rats, Wistar; Tyrosine

Peroxynitrite (ONOO(-)) formation triggers oxidative/nitrative stress and contributes to exacerbated myocardial ischemia/reperfusion (MI/R) injury. Catalpol, an iridoid glycoside, abundantly found in the roots of Rehmannia glutinosa L. that is included in the family Phrymaceae in the order Lamiales, endemic to China, was found to have neuroprotective effects. However, the effect of catalpol on MI/R injury has not been identified.. This study investigated whether catalpol attenuates oxidative/nitrative stress in acute MI/R.. Adult male rats were subjected to 30 min of myocardial ischemia and 3 h of reperfusion and were treated with saline, catalpol (5 mg/kg, i.p., 5 min before reperfusion) or catalpol plus wortmannin (15 µg/kg intraperitoneally injected 15 min before reperfusion).. Pretreatment with catalpol significantly improved cardiac functions, reduced myocardial infarction, apoptosis and necrosis of cardiomyocytes after MI/R (all p < 0.05). Meanwhile, ONOO(-) formation was markedly reduced after catalpol treatment (3.01 ± 0.22 vs. 4.66 ± 0.53 pmol/mg protein in vehicle, p < 0.05). In addition, catalpol increased Akt and endothelial nitric oxide synthase phosphorylation, nitric oxide (NO) production, anti-oxidant capacity and reduced MI/R-induced inducible nitric oxide synthase expression and superoxide anion (·O(2)(-)) production in I/R hearts. PI3K inhibitor wortmannin not only blocked catalpol-induced Akt activation, but also attenuated all the beneficial effects of catalpol. Suppression of ONOO(-) formation by either catalpol or an ONOO(-) scavenger uric acid (5 mg/kg) reduced myocardial infarct size in MI/R rats.. In conclusion, catalpol affords cardioprotection against MI/R insult by attenuating ONOO(-) formation, which is attributable to increased physiological NO and decreased ·O(2)(-) production.

Topics: Animals; Antioxidants; Apoptosis; Cardiotonic Agents; Disease Models, Animal; Down-Regulation; Enzyme Activation; Free Radical Scavengers; Injections, Intraperitoneal; Iridoid Glucosides; Male; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Necrosis; Nitric Oxide; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Oxidative Stress; Peroxynitrous Acid; Phosphatidylinositol 3-Kinase; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Time Factors; Tyrosine

High-mobility group box 1 (HMGB1) is a nuclear protein actively secreted by immune cells and passively released by necrotic cells that initiates pro-inflammatory signalling through binding to the receptor for advance glycation end-products. HMGB1 has been established as a key inflammatory mediator during myocardial infarction, but the proximal mechanisms responsible for myocardial HMGB1 expression and release in this setting remain unclear. Here, we investigated the possible involvement of peroxynitrite, a potent cytotoxic oxidant formed during myocardial infarction, on these processes.. The ability of peroxynitrite to induce necrosis and HMGB1 release in vitro was evaluated in H9c2 cardiomyoblasts and in primary murine cardiac cells (myocytes and non-myocytes). In vivo, myocardial HMGB1 expression and nitrotyrosine content (a marker of peroxynitrite generation) were determined following myocardial ischaemia and reperfusion in rats, whereas peroxynitrite formation was inhibited by two different peroxynitrite decomposition catalysts: 5,10,15,20-tetrakis(4-sulphonatophenyl) porphyrinato iron (III) (FeTPPS) or Mn(III)-tetrakis(4-benzoic acid) porphyrin chloride (MnTBAP). In all types of cells studied, peroxynitrite (100 μM) elicited significant necrosis, the loss of intracellular HMGB1, and its passive release into the medium. In vivo, myocardial ischaemia-reperfusion induced significant myocardial necrosis, cardiac nitrotyrosine formation, and marked overexpression of myocardial HMGB1. FeTPPS reduced nitrotyrosine, decreased infarct size, and suppressed HMGB1 overexpression, an effect that was similarly obtained with MnTBAP.. These findings indicate that peroxynitrite represents a key mediator of HMGB1 overexpression and release by cardiac cells and provide a novel mechanism linking myocardial oxidative/nitrosative stress with post-infarction myocardial inflammation.

Topics: Animals; Apoptosis; Cells, Cultured; HMGB1 Protein; Male; Mice; Mice, Inbred C57BL; Mitogen-Activated Protein Kinases; Myoblasts, Cardiac; Myocardial Infarction; Necrosis; Peroxynitrous Acid; Rats; Rats, Wistar; Receptor for Advanced Glycation End Products; Receptors, Immunologic; Toll-Like Receptor 4; Tyrosine; Up-Regulation

It is well known that insulin possesses a cardioprotective effect and that insulin resistance is closely related to cardiovascular diseases. Peroxynitrite (ONOO(-)) formation may trigger oxidative/nitrative stress and represent a major cytotoxic effect in heart diseases. This study was designed to investigate whether insulin attenuates ONOO(-) generation and oxidative/nitrative stress in acute myocardial ischemia/reperfusion (MI/R). Adult male rats were subjected to 30 min of myocardial ischemia and 3 h of reperfusion. Rats randomly received vehicle, insulin, or insulin plus wortmannin. Arterial blood pressure and left ventricular pressure were monitored throughout the experiment. Insulin significantly improved cardiac functions and reduced myocardial infarction, apoptotic cell death, and blood creatine kinase/lactate dehydrogenase levels following MI/R. Myocardial ONOO(-) formation was significantly attenuated after insulin treatment. Moreover, insulin resulted in a significant increase in Akt and endothelial nitric oxide (NO) synthase (eNOS) phosphorylation, NO production, and antioxidant capacity in ischemic/reperfused myocardial tissue. On the other hand, insulin markedly reduced MI/R-induced inducible NOS (iNOS) and gp91(phox) expression in cardiac tissue. Inhibition of insulin signaling with wortmannin not only blocked the cardioprotection of insulin but also markedly attenuated insulin-induced antioxidative/antinitrative effect. Furthermore, the suppression on ONOO(-) formation by either insulin or an ONOO(-) scavenger uric acid reduced myocardial infarct size in rats subjected to MI/R. We concluded that insulin exerts a cardioprotective effect against MI/R injury by blocking ONOO(-) formation. Increased physiological NO production (via eNOS phosphorylation) and superoxide anion reduction contribute to the antioxidative/antinitrative effect of insulin, which can be reversed by inhibiting phosphatidylinositol 3'-kinase. These results provide important novel information on the mechanisms of cardiovascular actions of insulin.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Caspase 3; Creatine Kinase; Electrocardiography; Heart Function Tests; Hypoglycemic Agents; In Situ Nick-End Labeling; Insulin; L-Lactate Dehydrogenase; Male; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Necrosis; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reactive Nitrogen Species; Reperfusion Injury; Tyrosine

This study investigated the roles of inducible nitric oxide synthase (iNOS) in the failure of rat liver grafts from cardiac death donors (GCDD). Livers were explanted after 30-minute aorta clamping and implanted after 4-hour storage in University of Wisconsin solution. The iNOS expression increased slightly in grafts from non-cardiac death donors (GNCDD) but markedly in GCDD. Serum nitrite and nitrate and hepatic 3-nitrotyrosine adducts, indicators of NO and peroxynitrite production, respectively, were substantially higher after transplantation of GCDD than GNCDD. Production of reactive nitrogen species (RNS) was largely blocked by 1400W (N-[1-naphthyl]ethylenediamine dihydrochloride; 5 μM), a specific iNOS inhibitor. Alanine aminotransferase release, bilirubin, necrosis, and apoptosis were 6.4-fold, 6.5-fold, 2.3-fold, and 2.7-fold higher, respectively, after transplantation of GCDD than GNCDD. The inhibitor 1400W effectively blocked these alterations and also increased survival of GCDD to 80% from 33%. Increased RNS production and failure of GCDD were associated with activation of c-Jun-N-terminal kinase (JNK), an effect that was blocked by inhibition of iNOS. Inhibition of JNK also improved the outcome after transplantation of GCDD. Together, the data indicate that iNOS increases substantially in GCDD, leading to RNS overproduction, JNK activation, and more severe graft injury. Inhibitors of iNOS are suggested as effective therapies to improve the outcome after transplantation of GCDD.

Topics: Alanine Transaminase; Animals; Bilirubin; Death; Enzyme Inhibitors; Graft Rejection; Graft Survival; Imines; Liver; Liver Transplantation; Mitogen-Activated Protein Kinase 8; Mitogen-Activated Protein Kinase 9; Necrosis; Nitrates; Nitric Oxide Synthase Type II; Nitrites; Peroxynitrous Acid; Rats; Rats, Inbred Lew; Reactive Nitrogen Species; Tyrosine

Ascorbic acid (AA) is a potent antioxidant, and its neuroprotective effect has not been established yet. Using the Rice-Vannucci model, we examined the effect of AA on hypoxic-ischemic (HI) injury in the immature rat brain. Under isoflurane anesthesia, 7-day-old rat pups received 750 mg/kg of AA by intraperitoneal injection just before hypoxic exposure; 8% oxygen for 90 min. Vehicle controls received an equal volume of saline. AA decreased a macroscopic brain injury score at 48 and 168 h post-HI compared with vehicle controls (48 h post-HI, AA 1.38+/-0.45 vs. controls 2.94+/-0.24, p<0.05; 168 h post-HI, 1.13+/-0.44 vs. 2.50+/-0.25, p<0.05). AA injection significantly decreased the number of both necrotic and apoptotic cells in cortex, caudate putamen, thalamus and hippocampus, and also seemed to reduce the number of TUNEL-positive cells. Western blot analysis showed that AA significantly suppressed 150/145 kDa subunits of alpha-fodrin breakdown products (FBDP) in cortex, striatum, thalamus and hippocampus at 24 and 48 h post-HI, and also 120 kDa subunit of FBDP in all examined regions except for thalamus, which indicated that AA injection inhibited both calpain and caspase-3 activation. Western blot analysis of nitrotyrosine failed to show inhibition of free radical production by AA, however, our results show that AA inhibits both necrotic and apoptotic cell death and that AA is neuroprotective after HI in immature rat brain.

Topics: Analysis of Variance; Animals; Animals, Newborn; Antioxidants; Apoptosis; Ascorbic Acid; Blotting, Western; Brain; Brain Ischemia; Calpain; Carrier Proteins; Caspase 3; Enzyme Activation; In Situ Nick-End Labeling; Microfilament Proteins; Microscopy, Electron; Necrosis; Neurons; Neuroprotective Agents; Rats; Tyrosine

There are few reports about the direct toxic effects of hyperhomocysteinemia on the liver. We investigated oxidative and nitrosative stresses and apoptotic and necrotic changes in the liver of rats fed a high-methionine (HM) diet (2%, w/w) for 6 mo. We also investigated whether taurine, an antioxidant amino acid, is protective against an HM-diet-induced toxicity in the liver.. Lipid peroxide levels, nitrotyrosine formation, and non-enzymatic and enzymatic antioxidants were determined in livers of rats fed an HM diet. In addition, apoptosis-related proteins, proapoptotic Bax and antiapoptotic B-cell lymphoma-2 expressions, apoptotic cell count, histopathologic appearance in the liver, and alanine transaminase and aspartate transaminase activities in the serum were investigated.. Plasma homocysteine levels and serum alanine transaminase and aspartate transaminase activities were increased after the HM diet. This diet resulted in increases in lipid peroxide and nitrotyrosine levels and decreases in non-enzymatic and enzymatic antioxidants in liver homogenates in rats. Bax expression increased, B-cell lymphoma-2 expression decreased, and apoptotic cell number increased in livers of rats fed an HM diet. Inflammatory reactions, microvesicular steatosis, and hepatocyte degeneration were observed in the liver after the HM diet. Taurine (1.5%, w/v, in drinking water) administration and the HM diet for 6 mo was found to decrease serum alanine transaminase and aspartate transaminase activities, hepatic lipid peroxide levels, and nitrotyrosine formation without any change in serum homocysteine levels. Decreases in Bax expression, increases in B-cell lymphoma-2 expression, decreases in apoptotic cell number, and amelioration of histopathologic findings were observed in livers of rats fed with the taurine plus HM diet.. Our results indicate that taurine has protective effects on hyperhomocysteinemia-induced toxicity by decreasing oxidative and nitrosative stresses, apoptosis, and necrosis in the liver.

Topics: Alanine Transaminase; Animals; Antioxidants; Apoptosis; Aspartate Aminotransferases; bcl-2-Associated X Protein; Hyperhomocysteinemia; Inflammation; Lipid Peroxides; Liver; Male; Malondialdehyde; Methionine; Necrosis; Nitrosation; Oxidative Stress; Rats; Rats, Wistar; Taurine; Tyrosine

Doxorubicin (DOX) is a potent available antitumor agent; however, its clinical use is limited because of its cardiotoxicity. Cell death is a key component in DOX-induced cardiotoxicity, but its mechanisms are elusive. Here, we explore the role of superoxide, nitric oxide (NO), and peroxynitrite in DOX-induced cell death using both in vivo and in vitro models of cardiotoxicity. Western blot analysis, real-time PCR, immunohistochemistry, flow cytometry, fluorescent microscopy, and biochemical assays were used to determine the markers of apoptosis/necrosis and sources of NO and superoxide and their production. Left ventricular function was measured by a pressure-volume system. We demonstrated increases in myocardial apoptosis (caspase-3 cleavage/activity, cytochrome c release, and TUNEL), inducible NO synthase (iNOS) expression, mitochondrial superoxide generation, 3-nitrotyrosine (NT) formation, matrix metalloproteinase (MMP)-2/MMP-9 gene expression, poly(ADP-ribose) polymerase activation [without major changes in NAD(P)H oxidase isoform 1, NAD(P)H oxidase isoform 2, p22(phox), p40(phox), p47(phox), p67(phox), xanthine oxidase, endothelial NOS, and neuronal NOS expression] and decreases in myocardial contractility, catalase, and glutathione peroxidase activities 5 days after DOX treatment to mice. All these effects of DOX were markedly attenuated by peroxynitrite scavengers. Doxorubicin dose dependently increased mitochondrial superoxide and NT generation and apoptosis/necrosis in cardiac-derived H9c2 cells. DOX- or peroxynitrite-induced apoptosis/necrosis positively correlated with intracellular NT formation and could be abolished by peroxynitrite scavengers. DOX-induced cell death and NT formation were also attenuated by selective iNOS inhibitors or in iNOS knockout mice. Various NO donors when coadministered with DOX but not alone dramatically enhanced DOX-induced cell death with concomitant increased NT formation. DOX-induced cell death was also attenuated by cell-permeable SOD but not by cell-permeable catalase, the xanthine oxidase inhibitor allopurinol, or the NADPH oxidase inhibitors apocynine or diphenylene iodonium. Thus, peroxynitrite is a major trigger of DOX-induced cell death both in vivo and in vivo, and the modulation of the pathways leading to its generation or its effective neutralization can be of significant therapeutic benefit.

Topics: Animals; Antibiotics, Antineoplastic; Antioxidants; Apoptosis; Cell Line; Dose-Response Relationship, Drug; Doxorubicin; Enzyme Inhibitors; Free Radical Scavengers; Heart Diseases; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitochondria, Heart; Myocardial Contraction; Myocytes, Cardiac; Necrosis; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase Type II; Peroxynitrous Acid; Poly(ADP-ribose) Polymerases; Superoxides; Tyrosine; Ventricular Function, Left; Ventricular Pressure

Unilateral hypoxia-ischemia (HI) was induced in C57/BL6 male mice on postnatal day (P) 5, 9, 21 and 60, corresponding developmentally to premature, term, juvenile and adult human brains, respectively. HI duration was adjusted to obtain a similar extent of brain injury at all ages. Apoptotic mechanisms (nuclear translocation of apoptosis-inducing factor, cytochrome c release and caspase-3 activation) were several-fold more pronounced in immature than in juvenile and adult brains. Necrosis-related calpain activation was similar at all ages. The CA1 subfield shifted from apoptosis-related neuronal death at P5 and P9 to necrosis-related calpain activation at P21 and P60. Oxidative stress (nitrotyrosine formation) was also similar at all ages. Autophagy, as judged by the autophagosome-related marker LC-3 II, was more pronounced in adult brains. To our knowledge, this is the first report demonstrating developmental regulation of AIF-mediated cell death as well as involvement of autophagy in a model of brain injury.

Topics: Aging; Animals; Apoptosis; Apoptosis Inducing Factor; Autophagy; Brain Injuries; Calpain; Caspase 3; Caspases; Cell Death; Cytochromes c; Disease Models, Animal; Flavoproteins; Hypoxia-Ischemia, Brain; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Microtubule-Associated Proteins; Mitochondria; Necrosis; Neurons; Protein Transport; Tyrosine

Elevated LPS and elevated cytochrome P-450 2E1 (CYP2E1) in liver are two major independent risk factors in alcoholic liver disease. We investigated possible synergistic effects of the two risk factors in causing oxidative stress and liver injury. Sprague-Dawley rats were injected intraperitoneally with pyrazole (inducer of CYP2E1) for 2 days, and then LPS was injected via tail vein. Other rats were treated with pyrazole alone or LPS alone or saline. Eight hours later, blood was collected and livers were excised. Pathological evaluation showed severe inflammatory responses and necroses only in liver sections from rats in the pyrazole plus LPS group; blood transaminase levels were significantly elevated only in the combination group. Activities of caspase-3 and -9 and positive terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining were highest in the LPS alone and the LPS plus pyrazole group, with no significant difference between the two groups. Lipid peroxidation and protein carbonyls in liver homogenate as well as in situ superoxide production were maximally elevated in the LPS plus pyrazole group. Levels of nitrite plus nitrate and inducible nitric oxide (NO) synthase (iNOS) content were comparably elevated in LPS alone and the LPS plus pyrazole group; however, 3-nitrotyrosine adducts were elevated in the combined group but not the LPS group. It is likely that LPS induction of iNOS, which produces NO, coupled to pyrazole induction of CYP2E1 which produces superoxide, sets up conditions for maximal peroxynitrite formation and production of 3-nitrotyrosine adducts. CYP2E1 activity and content were elevated in the pyrazole and the LPS plus pyrazole groups. Immunohistochemical staining indicated that distribution of CYP2E1 was in agreement with that of necrosis and production of superoxide. These results show that pyrazole treatment enhanced LPS-induced necrosis, not apoptosis. The enhanced liver necrosis appears to involve an increase in oxidative and nitrosative stress generated by the combination of LPS plus elevated CYP2E1 levels.

Topics: Animals; Apoptosis; Chemical and Drug Induced Liver Injury; Cytochrome P-450 CYP2E1; Drug Synergism; Enzyme Inhibitors; Lipid Peroxidation; Lipopolysaccharides; Liver; Male; Necrosis; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oxidative Stress; Proteins; Pyrazoles; Rats; Rats, Sprague-Dawley; Superoxides; Tyrosine

Perfluorochemicals (PFCs) may exert a neuroprotective function in the early phase of ischemia by improving the oxygen supply to the endangered tissue. We have, therefore, investigated the effect of Oxycyte, a second-generation perfluorocarbon solution, on the extent of early ischemic brain damage in a model of permanent focal cerebral ischemia.. Eight hours of permanent focal cerebral ischemia was induced in isoflurane anesthetized male Sprague-Dawley rats by unilateral middle cerebral artery (MCA) thread occlusion under the control of laser Doppler flowmetry (LDF). Animals were assigned to one of the following treatment groups: nO2-NaCl and hO2-NaCl-NaCl (0.9%, 1 ml/100 g i.v.) and nO2-Oxycyte and hO2-Oxycyte-Oxycyte (1 ml/100 g i.v.). The injection of NaCl or Oxycyte was performed immediately after MCA occlusion. After injection, breathing was changed to pure oxygen in groups hO2-NaCl and hO2-Oxycyte while animals in groups nO2-NaCl and nO2-Oxycyte were allowed to breathe air. The necrotic volume was calculated from serial coronal sections stained with silver-nitrate. In addition, nitrotyrosine production was studied by immunohistochemistry.. Upon MCA occlusion, animals showed a reduction of cerebral blood flow of approximately 80% of the LDF signal in all groups. Hemodynamic and metabolic parameters were not affected by the infusion of Oxycyte. The total infarct volume was reduced in hO2-Oxycyte animals [group nO2-NaCl: 341+/-31 mm3 (mean+/-SD), group hO2-NaCl: 351+/-33 mm3, group nO2-Oxycyte: 354+/-24 mm3, and group hO2-Oxycyte: 300+/-29 mm3, p < 0.05 versus all other groups]. Moreover, hO2-Oxycyte animals showed lesser intensity of nitrotyrosine staining when compared with hO2-NaCl animals.. These results suggest that Oxycyte administered immediately after the onset of vascular occlusion may exert neuroprotective effects in the early phase of brain ischemia.

Topics: Analysis of Variance; Animals; Blood Gas Analysis; Brain Ischemia; Cerebrovascular Circulation; Disease Models, Animal; Drug Therapy, Combination; Fluorocarbons; Immunohistochemistry; Infarction, Middle Cerebral Artery; Laser-Doppler Flowmetry; Male; Necrosis; Neuroprotective Agents; Oxygen; Peroxynitrous Acid; Rats; Rats, Sprague-Dawley; Silver Staining; Time Factors; Tyrosine

Hepatic injury by d-galactosamine (d-GalN) is a suitable experimental model of hepatocellular injury. The induction of oxidative and nitrosative stress participates during d-GalN-induced cell death in cultured rat hepatocytes. This study aimed to identify protein expression changes during the induction of apoptosis and necrosis by d-GalN in cultured human hepatocytes.. A proteomic approach was used to identify the proteins involved and those altered by tyrosine nitration. A high dose of d-GalN (40 mM) was used to induce apoptosis and necrosis in primary culture of human hepatocytes. Cellular lysates prepared at different times after addition of d-GalN were separated by two-dimensional electrophoresis. Gel spots with an altered expression and those matching nitrotyrosine-immunopositive proteins were excised and analyzed by mass spectrometry.. d-GalN treatment upregulated microsomal cytochrome b5, fatty acid binding protein and manganese superoxide dismutase, and enhanced annexin degradation. d-GalN increased tyrosine nitration of four cytosolic (Hsc70, Hsp70, annexin A4 and carbonyl reductase) and three mitochondrial (glycine amidinotransferase, ATP synthase beta chain, and thiosulfate sulfurtransferase) proteins in human hepatocytes.. The results provide evidences that oxidative stress and nitric oxide-derived reactive oxygen intermediates induce specific alterations in protein expression that may be critical for the induction of apoptosis and necrosis by d-GalN in cultured human hepatocytes.

Topics: Apoptosis; Cell Death; Cells, Cultured; Galactosamine; Hepatocytes; Humans; Necrosis; Nitrates; Oxidative Stress; Proteins; Proteomics; Tyrosine

It is still controversial whether a major mode of cell death during hepatic ischemia-reperfusion (I/R) injuries is apoptosis or necrosis. Moreover, the correlation between these cell deaths and the effects of a novel inducible nitric oxide synthase inhibitor (ONO-1714) has not been studied before.. Pigs were subjected to 180 min of hepatic warm I/R under extracorporeal circulation. The control group was not administered ONO-1714. In the ONO-1714 group, ONO-1714 was administered 5 min before ischemia at a dose of 0.05 mg/kg through a portal vein catheter. The apoptotic and necrotic changes after reperfusion were examined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and hematoxylin-eosin staining. Nitrotyrosine, active caspase-3, and cytochrome c were examined by immunohistochemistry. The plasma NO + NO, aspartate aminotransferase, and lactate dehydrogenase levels were also examined.. In the control group, the frequency of apoptotic cells was only 2.6%; nevertheless, that of necrotic cells was 37% at 24 hr after reperfusion. ONO-1714 significantly attenuated apoptosis and necrosis, the expression of nitrotyrosine, and the increases of the plasma aspartate aminotransferase, lactate dehydrogenase, and NO(2)- + NO(3)- levels in the reperfusion phase.. A major mode of cell death during hepatic warm I/R injury was necrosis, and apoptosis was not dominant. These necrotic changes were caused by the excess production of peroxynitrite, and ONO-1714 greatly attenuated I/R injuries as the result of inhibition of the peroxynitrite production.

Topics: Amidines; Animals; Apoptosis; Aspartate Aminotransferases; DNA; Enzyme Inhibitors; Female; Hepatocytes; Heterocyclic Compounds, 2-Ring; Hot Temperature; In Situ Nick-End Labeling; Ischemia; L-Lactate Dehydrogenase; Liver; Liver Circulation; Microscopy, Confocal; Microscopy, Electron; Necrosis; Nitrates; Nitric Oxide Synthase; Nitrites; Reperfusion Injury; Swine; Time Factors; Tyrosine

Hemorrhagic shock and resuscitation cause hepatocellular damage by mechanisms involving oxidative stress. However, the sources of free radicals mediating hepatocellular injury remain controversial. Thus, this study tested the hypothesis that NADPH oxidase plays a role in producing hepatocellular injury after hemorrhagic shock and resuscitation. Both wild-type and NADPH oxidase-deficient mice (p47(phox) knockout mice) were subjected to hemorrhagic shock (3 h at 30 mmHg). The mice were resuscitated over 30 min with the shed blood and additional lactated Ringer's solution (50% of the shed blood volume). Serum alanine aminotransferase (ALT) levels increased at 1 and 6 h postresuscitation in wild-type animals to 4735 +/- 1017 IU/L and 1450 +/- 275 IU/L (mean +/- SE), respectively, whereas in knockout mice, this ALT increase was blunted at both time points (732 +/- 241 IU/L and 328 +/- 69 IU/L, P < 0.05). Liver necrosis assessed histologically 6 h after the end of reperfusion was also attenuated in the knockout mice (3.5% +/- 0.95% of area vs. 0.9% +/- 0.26%, P < 0.05). In hemorrhaged wild-type mice, infiltrating neutrophils were twice as numerous compared with hemorrhaged NADPH oxidase-deficient animals 6 h after reperfusion. In knockout animals, hepatic 4-hydroxynonenal content, indicative of lipid peroxidation from reactive oxygen species, was blunted (6.7% +/- 0.6% vs. 26.4% +/- 2.3% of stained area, P < 0.05), as shown by immunohistochemistry. Immunohistochemical staining for 3-nitrotyrosine, indicative of reactive nitrogen species formation, was also blunted in the livers of knockout mice (11.6% +/- 2.8% vs. 37.4% +/- 3.4, P < 0.05). In conclusion, hemorrhagic shock and resuscitation cause hepatocellular damage via NADPH oxidase-mediated oxidative stress. The absence of NADPH oxidase substantially attenuates hepatocellular injury after hemorrhagic shock and resuscitation, blunts neutrophil infiltration, and decreases formation of reactive oxygen and reactive nitrogen species.

Topics: Alanine Transaminase; Animals; Chemotaxis, Leukocyte; Ischemia; Lipid Peroxidation; Liver; Mice; Mice, Inbred C57BL; Mice, Knockout; NADPH Oxidases; Necrosis; Neutrophils; Oxidative Stress; Peroxynitrous Acid; Phosphoproteins; Reperfusion Injury; Resuscitation; Shock, Hemorrhagic; Superoxides; Tyrosine

The goal of this study was to investigate the role of cardiac nerves on the response to 90-minute coronary artery stenosis (CAS), which reduced coronary blood flow by 40% for 90 minutes, and subsequent myocardial stunning after reperfusion in chronically instrumented conscious pigs. In pigs with regional cardiac denervation (CD), myocardial stunning was intensified, ie, at 12 hours reperfusion wall thickening (WT) was depressed more, P<0.05, in CD (-46+/-5%) as compared with intact pigs (-31+/-3%) and remained depressed in CD at 24 hours reperfusion (-45+/-6%). Although the TTC technique was negative for infarct, histopathological analysis revealed patchy necrosis present in 11+/-2% of the area at risk. In intact pigs, WT had essentially recovered at 24 hours without infarct. In CD pigs treated with either an antioxidant, N-2-mercaptopropionyl glycine (MPG, 100 mg/kg per hour) or systemic nitric oxide synthase inhibition using N(omega)-nitro-L-arginine (L-NA, 30 mg/kg for 3 days), recovery of wall thickening was similar to that in pigs with intact nerves and without evidence of infarct. Immunohistochemistry analysis for 3-nitrotyrosine in tissue after CAS and 1 hour reperfusion demonstrated enhanced peroxynitrite-related protein nitration in pigs with regional CD compared with pigs with intact cardiac nerves, and pigs with regional CD and MPG or L-NA. Thus, reperfusion after myocardial ischemia in the setting of CD results in enhanced stunning and development of infarct. The underlying mechanism appears to involve nitric oxide and reactive oxygen species.

Topics: Animals; Coronary Stenosis; Denervation; Enzyme Inhibitors; Heart; Hemodynamics; Immunohistochemistry; Models, Animal; Myocardial Reperfusion; Myocardial Stunning; Myocardium; Necrosis; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Norepinephrine; Reactive Oxygen Species; Swine; Tyrosine

The nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays a pivotal role in the induction of genes involved in the response to injury and inflammation. Dithiocarbamates are antioxidants that are potent inhibitors of NF-kappaB. This study tested the hypothesis that pyrrolidine dithiocarbamate (PDTC) attenuates experimental acute pancreatitis. Intraperitoneal injection of cerulein in mice resulted in severe, acute pancreatitis characterized by edema, neutrophil infiltration, tissue hemorrhage and necrosis, and elevated serum levels of amylase and lipase. Infiltration of pancreatic and lung tissue with neutrophils (measured as increase in myeloperoxidase activity) was associated with enhanced lipid peroxidation (increased tissue levels of malondialdehyde). Immunohistochemical examination demonstrated a marked increase in immunoreactivity for nitrotyrosine and intracellular adhesion molecule-1 in the pancreas and lung of cerulein-treated mice. In contrast, the degree of 1) pancreas and lung injury, 2) upregulation/expression of intracellular adhesion molecule-1, 3) staining for nitrotyrosine, and 4) lipid peroxidation was markedly reduced by pretreatment with PDTC. This study demonstrates that prevention of the activation of NF-kappaB by PDTC ameliorates the tissue injury associated with experimental murine acute pancreatitis and provides an important insight into the molecular biology of acute pancreatitis.

Topics: Amylases; Animals; Antioxidants; Blotting, Western; Ceruletide; Edema; I-kappa B Proteins; Immunohistochemistry; Inflammation; Intercellular Adhesion Molecule-1; Lipase; Lipid Peroxidation; Male; Mice; Necrosis; Neutrophils; NF-kappa B; NF-KappaB Inhibitor alpha; Pancreatitis; Peroxidase; Pyrrolidines; Rats; Thiocarbamates; Tyrosine; Up-Regulation

Gentamicin (GM) is an antibiotic whose clinical use is limited by its nephrotoxicity. Experimental evidences suggest a role of reactive oxygen species in GM-induced nephrotoxicity. In this work we explored the effect of diallyl sulfide (DAS), a garlic-derived compound with antioxidant properties, on GM-induced nephrotoxicity. Four groups of rats were studied: (1) Control, treated intragastrically with olive oil as a vehicle, (2) GM, treated subcutaneously with GM (125 mg/kg/day for 4 days), (3) DAS, treated intragastrically with DAS (50 mg/kg/day for 4 days), and (4) GM + DAS. Nephrotoxicity was made evident by: (1) the increase in creatinine and blood urea nitrogen in serum, (2) the increase in urinary excretion of N-acetyl-beta-D-glucosaminidase and total protein, and (3) necrosis of proximal tubular cells. These functional and structural alterations were prevented or ameliorated by DAS treatment. In addition, GM increased levels of renal oxidative stress markers nitrotyrosine and protein carbonyl groups which were also ameliorated by DAS in GM + DAS group. The mechanism by which DAS has a protective effect on GM-induced nephrotoxicity may be related, at least in part, to the decrease in oxidative stress in renal cortex.

Topics: Acetylglucosaminidase; Allyl Compounds; Animals; Anti-Bacterial Agents; Antioxidants; Blood Urea Nitrogen; Body Weight; Carbon; Creatinine; Gentamicins; Immunohistochemistry; Kidney; Kidney Cortex; Kidney Tubules; Male; Necrosis; Olive Oil; Oxidative Stress; Oxygen; Plant Oils; Rats; Rats, Wistar; Reactive Oxygen Species; Sulfides; Time Factors; Tyrosine

Acetaminophen (AAP) overdose causes formation of nitrotyrosine, a footprint of peroxynitrite, in centrilobular hepatocytes. The importance of peroxynitrite for the pathophysiology, however, is unclear. C3Heb/FeJ mice were treated with 300 mg/kg AAP. To accelerate the restoration of hepatic glutathione (GSH) levels as potential endogenous scavengers of peroxynitrite, some groups of animals received 200 mg of GSH/kg i.v. at different time points after AAP. AAP induced severe liver cell damage at 6 h. Total liver and mitochondrial glutathione levels decreased by >90% at 1 h but recovered to 75 and 45%, respectively, of untreated values at 6 h after AAP. In addition, the hepatic and mitochondrial glutathione disulfide (GSSG) content was significantly increased over baseline, suggesting a mitochondrial oxidant stress. Moreover, centrilobular hepatocytes stained for nitrotyrosine. Treatment with GSH at t = 0 restored hepatic GSH levels and completely prevented the mitochondrial oxidant stress, peroxynitrite formation, and liver cell injury. In contrast, treatment at 1.5 and 2.25 h restored hepatic and mitochondrial GSH levels but did not prevent the increase in GSSG formation. Nitrotyrosine adduct formation and liver injury, however, was substantially reduced. GSH treatment at 3 h after AAP was ineffective. Similar results were obtained when these experiments were repeated with glutathione peroxidase-deficient animals. Our data suggest that early GSH treatment (t = 0) prevented cell injury by improving the detoxification of the reactive metabolite of AAP. Delayed GSH treatment enhanced hepatic GSH levels, which scavenged peroxynitrite in a spontaneous reaction. Thus, peroxynitrite is an important mediator of AAP-induced liver cell necrosis.

Topics: Acetaminophen; Alanine Transaminase; Analgesics, Non-Narcotic; Animals; Antidotes; Chemical and Drug Induced Liver Injury; Glutathione; Immunohistochemistry; Injections, Intravenous; Liver; Male; Mice; Mice, Inbred C3H; Mitochondria, Liver; Necrosis; Peroxynitrous Acid; Serum Albumin, Bovine; Tyrosine

The hepatic centrilobular necrosis produced by the analgesic/antipyretic acetaminophen correlates with metabolic activation of the drug leading to its covalent binding to protein. However, the molecular mechanism of the toxicity is not known. Recent immunohistochemical analyses using an antinitrotyrosine antiserum indicated that nitrotyrosine protein adducts co-localized with the acetaminophen-protein adducts in the centrilobular cells of the liver. Nitration of proteins is believed to occur by peroxynitrite, a substance formed by the rapid reaction of superoxide with nitric oxide. Nitric oxide and superoxide may be formed by activated Kupffer cells or by other cells. Because we were unable to successfully utilize the commercial antiserum in Western blot analyses of liver fractions, we developed a new antiserum. With our antiserum, liver fractions from saline-treated control and acetaminophen-treated mice were successfully analyzed for nitrated proteins. The immunogen for this new antiserum was synthesized by coupling 3-nitro-4-hydroxybenzoic acid to keyhole limpet hemocyanin. A rabbit immunized with this adduct yielded a high titer of an antiserum that recognized BSA nitrated with peroxynitrite. Immunoblot analysis of nitrated BSA indicated that nitrotyrosine present in a protein sample could be easily detected at levels of 20 pmoles. Immunohistochemical analyses indicated that nitrotyrosine protein adducts were detectable in the centrilobular areas of the liver. Immunoblot analysis of liver homogenates from both saline-treated and acetaminophen-treated mice (300 mg/kg) indicate that the major nitrotyrosine protein adducts produced have molecular weights of 36 kDa, 44 kDa, and 85 kDa. The 85-kDa protein stained with the most intensity. The hepatic homogenates of the acetaminophen- treated mice showed significantly increased levels of all protein adducts.

Topics: Acetaminophen; Adjuvants, Immunologic; Analgesics, Non-Narcotic; Animals; Blotting, Western; Cattle; Chemical and Drug Induced Liver Injury; Enzyme-Linked Immunosorbent Assay; Hemocyanins; Immunoenzyme Techniques; Liver; Male; Mice; Mice, Inbred C57BL; Necrosis; Nitrates; Protein Binding; Proteins; Rabbits; Serum Albumin, Bovine; Sodium Chloride; Tyrosine

Despite recent investigations, the mechanisms responsible for intestinal epithelial injury during endotoxemia remain unclear. The present study tests the hypothesis that epithelial necrosis and/or apoptosis correlate with nitric oxide (NO) dysregulation in a nonischemic model of sepsis-induced ileal injury. To test this hypothesis, a well-established in situ, autoperfused, feline ileal preparation was employed. After endotoxin (lipopolysaccharide [LPS], 3 mg/ kg, intravenously; n = 9) or vehicle (control; n = 5) treatment, ileal segments were obtained at baseline, 2 and 4 h for simultaneous evaluations of cellular and mitochondrial ultrastructure, immunoprevalence of inducible nitric oxide synthase (iNOS) and 3-nitrotyrosine (a stable biomarker of peroxynitrite), and histochemical evidence of apoptosis. Epithelial necrosis was prominent by 2 h post-LPS, despite unaltered global ileal tissue oxygen content, blood volume, and blood flow. Significant evidence of apoptosis and increases in the immunoprevalence of iNOS and 3-nitrotyrosine were not evident until 4 h post-LPS. These results suggest that the early ileal mucosal necrosis may be due to LPS-induced activation of inflammatory pathways and/or microcirculatory disturbances, whereas NO dysregulation may participate in later events, including protein nitration and epithelial apoptosis.

Topics: Animals; Apoptosis; Cats; Ileum; Immunohistochemistry; Intestinal Mucosa; Lipopolysaccharides; Male; Mitochondria; Multiple Organ Failure; Necrosis; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oxygen Consumption; Sepsis; Tyrosine

The generation of reactive oxygen species (ROS) contributes to the pathogenesis of renal ischemia-reperfusion injury. The aim of this study was to investigate the effects of tempol in (1) an in vivo rat model of renal ischemia/reperfusion injury and on (2) cellular injury and death of rat renal proximal tubular (PT) cells exposed to oxidant stress in the form of hydrogen peroxide (H2O2).. Male Wistar rats underwent bilateral renal pedicle clamping for 45 minutes followed by reperfusion for six hours. Tempol (30 mg/kg/h), desferrioxamine (DEF; 40 mg/kg/h), or a combination of tempol (30 mg/kg/h) and DEF (40 mg/kg/h) were administered prior to and throughout reperfusion. Plasma concentrations of urea, creatinine, Na+, gamma-glutamyl transferase (gammaGT), aspartate aminotransferase (AST), and urinary Na+ and N-acetyl-beta-D-glucosaminidase (NAG) were measured for the assessment of renal function and reperfusion injury. Kidney myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels were measured for assessment of polymorphonuclear (PMN) cell infiltration and lipid peroxidation, respectively. Renal sections were used for histologic grading of renal injury and for immunohistochemical localization of nitrotyrosine and poly(ADP-ribose) synthetase (PARS). Primary cultures of rat PT cells were incubated with H2O2 (1 mmol/L for 4 h) either in the absence or presence of increasing concentrations of tempol (0.03 to 10 mmol/L), DEF (0.03 to 10 mmol/L), or a combination of tempol (3 mmol/L) or DEF (3 mmol/L). PT cell injury and death were determined by evaluating mitochondrial respiration and lactate dehydrogenase (LDH) release, respectively.. In vivo, tempol significantly reduced the increase in urea, creatinine, gammaGT, AST, NAG, and FENa produced by renal ischemia/reperfusion, suggesting an improvement in both renal function and injury. Tempol also significantly reduced kidney MPO activity and MDA levels, indicating a reduction in PMN infiltration and lipid peroxidation, respectively. Tempol reduced the histologic evidence of renal damage associated with ischemia/reperfusion and caused a substantial reduction in the staining for nitrotyrosine and PARS, suggesting reduced nitrosative and oxidative stress. In vitro, tempol significantly attenuated H2O2-mediated decrease in mitochondrial respiration and increase in LDH release from rat PT cells, indicating a reduction in cell injury and death. Both in vivo and in vitro, the beneficial actions of tempol were similar to those obtained using the Fe2+ chelator DEF. However, coadministration of DEF and tempol did not produce any additional beneficial actions against renal ischemia/reperfusion injury or against oxidative stress-mediated PT cell injury/death.. Our results suggest that the membrane-permeable radical scavenger, tempol, reduces the renal dysfunction and injury associated with ischemia/reperfusion of the kidney.

Topics: Acute Kidney Injury; Animals; Cell Membrane Permeability; Cell Separation; Cells, Cultured; Chelating Agents; Cyclic N-Oxides; Deferoxamine; Disease Models, Animal; Free Radical Scavengers; Hydrogen Peroxide; Kidney Glomerulus; Kidney Tubules, Proximal; Male; Malondialdehyde; Necrosis; Oxidants; Oxidative Stress; Peroxidase; Poly(ADP-ribose) Polymerases; Rats; Rats, Wistar; Reperfusion Injury; Spin Labels; Tyrosine

A free radical gas, nitric oxide, has many useful functions when produced under physiological conditions by neurons and endothelial cells. However, excess nitric oxide has been reported to exert cytotoxic effects by direct toxicity or by reaction with superoxide. The effect of nitric oxide on the microcirculation in the periphery of a flap remains unclear, and its effect on flap survival is also unknown because nitric oxide has a dual action. Thus, we attempted to clarify the effect of nitric oxide on survival of rat random pattern skin flaps by the use of an endothelial constitutive nitric oxide synthase inhibitor (i.p. administration of 50 mg/kg N(G)-nitro-L-arginine) and the substrate of nitric oxide synthase (i.p. administration of 1 g/kg L-arginine). Three kinds of experiments were done using a total number of 120 animals: (1) time course measurement of blood flow in the flap periphery was performed using a laser Doppler flowmeter (30 rats), (2) the length of the surviving area of flaps was measured 1 week after raising the flap (60 rats), and (3) Western blot analysis was used to determine the time course of changes in the amount of endothelial constitutive nitric oxide synthase and the formation of 3-nitro-L-tyrosine, which is a marker of peroxynitrite-mediated (i.e., nitric oxide-dependent) tissue damage (30 rats). Inhibition of endothelial constitutive nitric oxide synthase by N(G)-nitro-L-arginine significantly decreased the length of the surviving area of skin flap (p < 0.01 compared with the control), which was associated with a decrease in the blood flow of the proximal portion of the flap. On the other hand, exogenous L-arginine increased the survival length of skin flap significantly (p < 0.01 compared with the control), which was associated with an increase in blood flow of the distal portion of the flap even though there was nitric oxide-mediated oxidative tissue damage. These results suggest that nitric oxide produced by endothelial constitutive nitric oxide synthase plays a role in maintaining circulation in the skin flap periphery and that L-arginine administration contributes to reduction of ischemic necrosis in the skin flap.

Topics: Animals; Arginine; Blotting, Western; Endothelium, Vascular; Enzyme Inhibitors; Free Radicals; Graft Survival; Injections, Intraperitoneal; Ischemia; Laser-Doppler Flowmetry; Male; Microcirculation; Necrosis; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Oxidation-Reduction; Rats; Rats, Wistar; Regional Blood Flow; Skin; Skin Transplantation; Tyrosine

Considerable evidence indicates that free radical injury may underlie the pathologic changes in muscular dystrophies from mammalian and avian species. We have investigated the role of oxidative injury in muscle necrosis in mice with a muscular dystrophy due to a defect in the dystrophin gene (the mdx strain). In order to avoid secondary consequences of muscle necrosis, all experiments were done on muscle prior to the onset of the degenerative process (i.e. during the 'pre-necrotic' phase) which lasted up to 20 days of age in the muscles examined. In pre-necrotic mdx muscle, there was an induction of expression of genes encoding antioxidant enzymes, indicative of a cellular response to oxidative stress. In addition, the levels of lipid peroxidation were greater in mdx muscle than in the control. Since the free radical nitric oxide (NO*) has been shown to mediate oxidative injury in various disease states, and because dystrophin has been shown to form a complex with the enzyme nitric oxide synthase, we examined pre-necrotic mdx muscle for evidence of NO*-mediated injury by measuring cellular nitrotyrosine formation. By both immunohistochemical and electrochemical analyses, no evidence of increased nitrotyrosine levels in mdx muscle was detected. Therefore, although no relationship with NO*-mediated toxicity was found, we found evidence of increased oxidative stress preceding the onset of muscle cell death in dystrophin-deficient mice. These results lend support to the hypothesis that free radical-mediated injury may contribute to the pathogenesis of muscular dystrophies.

Topics: Animals; Gene Expression; Mice; Mice, Inbred C57BL; Mice, Inbred mdx; Muscles; Necrosis; Nitric Oxide; Oxidative Stress; Oxidoreductases; Reference Values; Tyrosine