Peroxynitrite is a potent oxidant formed from the reaction between superoxide radicals and NO in a one-toone stoichiometry. This reaction occurs at 6.7310 mol/L z s,1 and it is essentially irreversible because of its highly exothermic nature. Therefore, the reaction is diffusionlimited, and it out-competes the reaction of superoxide dismutase for superoxide radicals, which proceeds at a rate of...

Most thymocytes are deleted by thymic selection. The mechanisms of cell death are far from being clear. Peroxynitrite is a powerful oxidant produced in vivo by the reaction of superoxide (O2*-) with nitric oxide (NO*) and is able to mediate apoptosis. The aim of this study was to analyze whether NO and peroxynitrite could play a role in human thymocyte apoptosis. The results indicate that 3-(4-...

BACKGROUND Increased oxidative stress and dysregulation of nitric oxide have been implicated in the cardiotoxicity of doxorubicin (DOX), a commonly used antitumor agent. Peroxynitrite is a reactive oxidant produced from nitric oxide and superoxide in various forms of cardiac injury. Using a novel metalloporphyrinic peroxynitrite decomposition catalyst, FP15, and nitric oxide synthase inhibitors...

The reaction of hydrogen sulfide (H2S) with peroxynitrite (a key mediator in numerous pathological states) was studied in vitro and in different cellular models. The results show that H2S can scavenge peroxynitrite with a corresponding second order rate constant of 3.3 ± 0.4 × 10³ M⁻¹·s⁻¹ at 23°C (8 ± 2 × 10³ M⁻¹·s⁻¹ at 37°C). Activation parameters for the reaction (ΔH‡, ΔS‡ and ΔV‡) revealed t...

Peroxynitrite is a potent oxidizing and nitrating species formed in a diffusion-limited reaction between nitrogen monoxide and superoxide. It induces apoptosis through unknown mechanisms and is believed to interfere with receptor tyrosine kinase signalling through nitration of tyrosine residues. One pathway emanating from receptor tyrosine kinases is that leading to activation of the anti-apopt...

Malignant gliomas are the most common primary brain tumors in adults, and the most malignant form, glioblastoma multiforme (GBM), is usually rapidly fatal. Most GBMs do not have p53 mutations, although the p53 tumor suppressor pathway appears to be inactivated. GBMs grow in a hypoxic and inflammatory microenvironment, and increased levels of the free radicals nitric oxide (NO) and superoxide (O...

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 recei...

Monocytes and macrophages are part of the first-line defense against bacterial, fungal, and viral infections during host immune responses; they express high levels of proinflammatory cytokines and cytotoxic molecules, including nitric oxide, reactive oxygen species, and their reaction product peroxynitrite. Peroxynitrite is a short-lived oxidant and a potent inducer of cell death. Honey, in add...

Hyperoxia exposure induces capillary endothelial cell apoptosis in the developing retina, leading to vaso-obliteration followed by proliferative retinopathy. Previous in vivo studies have shown that endothelial nitric oxide synthase (NOS3) and peroxynitrite are important mediators of the vaso-obliteration. Now we have investigated the relationship between hyperoxia, NOS3, peroxynitrite, and end...