Ae. Dikalova et al., An in vivo ESR spin-trapping study: Free radical generation in rats from formate intoxication - role of the Fenton reaction, P NAS US, 98(24), 2001, pp. 13549-13553
Citations number
40
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Electron spin resonance spectroscopy has been used to study free radical ge
neration in rats with acute sodium formate poisoning. The in vivo spin-trap
ping technique was used with alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone (PO
BN), which reacts with free radical metabolites to form radical adducts, wh
ich were detected in the bile and urine samples from Fischer rats. The use
of [C-13]-sodium formate and computer simulations of the spectra identified
the 12-line spectrum as arising from the POBN/carbon dioxide anion radical
adduct. The identification of POBN/(CO2-)-C-. radical adduct provides dire
ct electron spin resonance spectroscopy evidence for the formation of (CO2-
)-C-. radicals during acute intoxication by sodium formate, suggesting a fr
ee radical metabolic pathway. To study the mechanism of free radical genera
tion by formate, we tested several known inhibitors. Both allopurinol, an i
nhibitor of xanthine oxidase, and aminobenzotriazole, a cytochrome P450 inh
ibitor, decreased free radical formation from formate, which may imply a de
pendence on hydrogen peroxide. In accord with this hypothesis, the catalase
inhibitor 3-aminotriazole caused a significant increase in free radical fo
rmation. The iron chelator Desferal decreased the formation of free radical
s up to 2-fold. Presumably, iron plays a role in the mechanism of free radi
cal generation by formate via the Fenton reaction. The detection of formate
free radical metabolites generated in vivo and the key role of the Fenton
reaction in this process may be important for understanding the pathogenesi
s of both formate and methanol intoxication.