nitrogen-dioxide has been researched along with dihydrorhodamine-123* in 2 studies
2 other study(ies) available for nitrogen-dioxide and dihydrorhodamine-123
| Article | Year |
|---|---|
Kinetics of reaction of nitrogen dioxide with dihydrorhodamine and the reaction of the dihydrorhodamine radical with oxygen: implications for quantifying peroxynitrite formation in cells.
Dihydrorhodamine 123 (RhH2) has been used to detect 'reactive nitrogen species', including peroxynitrite and its radical decomposition products, peroxynitrite probably oxidizing RhH2 to rhodamine (Rh) via radical products rather than directly. In this study, the radical intermediate (RhH(.)) was generated by pulse radiolysis, and shown to react with oxygen with a rate constant k approximately 7 x 10(8) M(-1) s(-1). This fast reaction was exploited in experiments observing Rh being formed slowly (k approximately 4-7 x 10(5) M(-1) s(-1)) from oxidation of RhH2 by nitrogen dioxide in a rate-limiting step, >1000-fold slower than the corresponding oxidation by carbonate radicals. The time-dependent uptake of RhH2 into mammalian cells was measured, with average intracellular levels reaching only approximately 10 microM with the protocol used. The combination of low loading and relatively low reactivity of oxidants towards RhH2 compared to competing cellular nucleophiles suggests rather a small fraction of peroxynitrite-derived radicals (mainly CO3(.-)) may be scavenged intracellularly by RhH2. Topics: Animals; Cell Line; Cricetinae; Fibroblasts; Free Radicals; Kinetics; Nitrogen Dioxide; Oxygen; Peroxynitrous Acid; Rhodamines | 2009 |
Reactivity of 2',7'-dichlorodihydrofluorescein and dihydrorhodamine 123 and their oxidized forms toward carbonate, nitrogen dioxide, and hydroxyl radicals.
The aim of this study was to investigate the oxidation of two common fluorescent probes, dichlorodihydrofluorescein (DCFH2) and dihydrorhodamine (DHR), and their oxidized forms, dichlorofluorescein and rhodamine, by the radical products of peroxynitrite chemistry, *OH, NO2*, and CO3*-. At pH 8.0-8.2, rate constants for the interaction of carbonate radical with probes were estimated to be 2.6 x 10(8) x M(-1) s(-1) for DCFH2 and 6.7 x 10(8) M(-1) s(-1) for DHR. Nitrogen dioxide interacted more slowly than carbonate radical with these probes: the rate constant for the interaction between NO2* and DCFH2 was estimated as 1.3 x 10(7) M(-1) s(-1). Oxidation of DHR by nitrogen dioxide led to the production of rhodamine, but the kinetics of these reactions were complex. Hydroxyl radical interacted with both probes with rate constants close to the diffusion-controlled limit. We also found that oxidized forms of these fluorescent probes reacted rapidly with carbonate, nitrogen dioxide, and hydroxyl radicals. These data suggest that probe oxidation may often be in competition with reaction of the radicals with cellular antioxidants. Topics: Antioxidants; Carbonates; Diffusion; Fluoresceins; Free Radicals; Hydrogen-Ion Concentration; Hydroxyl Radical; Kinetics; Models, Chemical; Nitrogen Dioxide; Oxygen; Rhodamines; Spectrometry, Fluorescence; Spectrophotometry; Time Factors | 2005 |