Ascorbyl free radical as a reliable indicator of free‐radical‐mediated myocardial ischemic and post‐ischemic injury

Abstract

The real-time kinetics of the release of ascorbyl free radicals in the coronary perfusate from isolated rat hearts submitted to an ischemia/reperfusion sequence has been achieved by continuous-flow ESR using high-speed acquisition techniques. Enhanced ESR detection of ascorbyl free radicals was obtained by addition of dimethyl sulfoxide (Me,SO), a strong cation chelator and oxidizing agent. A continuous-flow device allowed a direct monitoring of the ascorbyl free radical and/or ascorbate leakage in coronary perfusate by observation of the ascorbyl radical doublet (aH = 0.188 mT and g = 2.0054).1. The results showed that ascorbyl free radical release occurred mainly during sequences of low-flow ischemia (90 min) coupled or not with 30 min of zero-flow ischemia followed by reperfusion (60 min). The kinetic profiles of ascorbyl-free-radical detection confirm in quantitative terms the expected correlation between the duration of the ischemic insult and the magnitude of ascorbate extracellular release upon reperfusion. There is indication that ascorbyl free radical depletion could be secondary to oxygen-derived-free-radical-induced cellular damage.2. The amount of residual ascorbic acid was quantitated on myocardial tissue at the end of reperfusion using Me2S0 as extracting solvent. Intense oxidation of ascorbate and chemical stabilization of the resulting free radical species provided by MezSO allowed ESR measurement of a marked tissue ascorbate depletion related to the duration of ischemia.3. Perfusion of superoxide dismutase during low-flow ischemia and the first 10 min of reperfusion greatly inhibited both extracellular release and endogenous ascorbate depletion. These results suggest that the ascorbate redox system constitutes a

Colitis and Colitis-Associated Cancer Are Exacerbated in Mice Deficient for Tumor Protein 53-Induced Nuclear Protein 1

“…Thawed samples were quickly introduced into a standard aqueous flat cell which was fitted within the cavity of a Bruker ESP 300 (Karlsruhe, Germany) X-band (9.8 GHz) ESR spectrometer equipped with a TM110 cavity and operating at a field modulation of 100-kHz and a microwave power of 10 mW. Spectral acquisition was initiated at room temperature 60 s after either the addition of DMSO or the complete thawing of the DEPMPO- was performed according to the literature (16,42,44). Free-radical concentrations were derived from double integrals of the simulated spectra obtained with either WinSim software (13) or the program of Rockenbauer and Korecz (48).…”

“…6A and B). We have previously shown that the concentration of this AFR-DMSO complex is representative of the ascorbate content of the plasma (42,44). In untreated WT mice, the baseline AFR-DMSO concentration corresponded to the signal yielded by 40 to 50 M sodium ascorbate (Fig.…”

Monoamine-dependent Production of Reactive Oxygen Species Catalyzed by Pseudoperoxidase Activity of Human Hemoglobin

“…For measurements of Asc  production in the autoxidized Hb solution, an ESR method described by Pietri et al 18) was modiˆed. 14) Brie‰y, Hb (25 mg W ml) autoxidized in PBS was mixed with 1 mM ascorbate.…”

“…Production of Asc  as a measure of Hb-catalyzed monoamine radical formation Addition of monoamines to Hb solution containing 2 mM ascorbate and 1 mM H 2 O 2 induced an ESR spectrum with a characteristic doublet signal of Asc  (hyperˆne splitting constant＝0.188 mT, g value＝ 2.005), 18,19) but no signal of Asc  was detected in the absence of ascorbate (Fig. 4).…”

The role of cyclooxygenase-derived oxidative stress in surgically induced lymphedema in a mouse tail model

“…It is possible that ascorbyl radical generation occurred secondarily to oxygen-derived freeradical-induced cellular damage (Pietri et al, 1990).…”