Trapping of free radicals with PBN during myocardial ischemia and reperfusion

Trapping of free radicals with PBN during myocardial ischemia and reperfusion 

Highly reactive and short-lived free radicals can react with spin traps to form a stable spin adduct. The resulting spin adduct can be detected and identified by ESR spectroscopy. In our model the radical adduct exits the coronary vasculature via the right heart in aqueous bicarbonate-buffered media. Under these conditions the radical adducted to the spin trap PBN rapidly degrades to products that are undetectable by ESR spin trapping. Kotake and Janzen [127] have recently reported that the lifetime of PBN/ OH adduct is dependent on the pH of the media the half-life of PBN/ OH adduct at pH 6 and 8 were 90 and 10 s, respectively. The PBN/ OH adduct was found to decay via the unimolecular 

The intracellular pH in the myocardial tissue during ischemia reportedly falls to 6.4 therefore, the PBN/ OH should be relatively more persistent under ischemic conditions as opposed to reperfusion. In aqueous solution, the decomposition of PBN/ OH is facilitated due to the ease with which the acidic (3-proton is dissociated. In contrast, the unimolecular decomposition of PBN/ OH becomes energetically difficult in non-protic solvents such as toluene and benzene. This may well account for the increased stability of PBN/ OH adduct in these solvents. 

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