ESR parameters of PBN adducts formed during myocardial ischemia and reperfusion

ESR parameters of PBN adducts formed during myocardial ischemia and reperfusion 

Because of their instability in aqueous solution, PBN adducts have been generally extracted in organic solvents prior to ESR analysis. A number of investigators [93,95,104-110] have used this extraction procedure in various models of myocardial ischemia and reperfusion. Table 3 shows the list of 

ESR parameters of PBN adducts and the tentative structures assigned for these adducts. Closer examination of Table 3 reveals that with the exception of one 

However, it must be pointed out that most of these studies cited in Table 3 were performed in blood-perfused models. In buffer-perfused models, PBN adduct formed in coronary effluents could be extracted into toluene within seconds. On the contrary, in blood-perfused models, the whole-blood samples require centrifugation to obtain plasma fractions that are then extracted into solvents. The processing of blood samples involves a delay time of several minutes. Therefore, it can be argued that PBN/ OH would not survive the delay time for sample processing. The actual half-life of PBN/ OH in the blood is, however, not known. 

It is conceivable that the PBN-lipid alkoxyl and PBN/ OH adducts have similar ESR parameters in various solvents [128], The PBN-lipid alkoxyl adduct, because it is more lipophilic, should be associated with the myocardial tissue and is unlikely to be released into the perfusate. The present study shows that PBN/ OH adduct is also fairly nonpolar. It is clear that other strategies to differentiate between the PBN/ OH and PBN-lipid alkoxyl adduct should be undertaken, such as isotopic substitution and mass spectrometry. 

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