Estimation of the postmortem duration of mouse tissue by electron spin resonance spectroscopy

Electron spin resonance (esr) method is a simple method for detecting various free radicals simultaneously and directly. however,esr spin trap method is unsuited to analyze weak esr signals in organs because of water-induced dielectric loss (widl). to minimize widl occurring in biotissues and to improve detection sensitivity to free radicals in tissues,esr cuvette was modified and used with 5,5-dimethtyl-1-pyrroline n-oxide (dmpo). the tissue samples were mouse brain,hart,lung,liver,kidney,pancreas,muscle,skin,and whole blood,where various esr spin adduct signals including dmpo-ascorbyl radical (asa*),dmpo-superoxide anion radical (ooh),and dmpo-hydrogen radical (h) signal were detected. postmortem changes in dmpo-asa* and dmpo-ooh were observed in various tissues of mouse. the signal peak of spin adduct was monitored until the 205th day postmortem. dmpo-asa* in liver (y = 113.8 - 40.7 log (day),r 1 = - 0.779,r 2 = 0.6,p <.001) was found to linearly decrease with the logarithm of postmortem duration days. therefore,dmpo-asa* signal may be suitable for detecting an oxidation stress tracer from tissue in comparison with other spin adduct signal on esr spin trap method. copyright 2011 shinobu ito et al.