Quantification of superoxide radical production in 4 vital organs of rats subjected to hemorrhagic shock

ObjectiveThe aim of this study was to measure the production of superoxide radical (O2−), a direct indicator of oxidative stress, in 4 vital organs of rats subjected to hemorrhagic shock. For this purpose, and for the first time, a new quantitative assay for the ex vivo measurement of O2− via an established 1:1 molar relationship between O2− and 2-OH-ethidium was used. The production of lipid hydroperoxides (LOOHs), a standard method of evaluation of oxidative stress, was also used for reasons of comparison.MethodsSixteen male Wistar rats were divided into 2 groups: sham and hemorrhagic shock, targeting to a mean arterial pressure of 30 to 40 mm Hg for 60 minutes. Three hours after resuscitation, tissues were collected for measurement of LOOHs and O2− production.ResultsHemorrhagic shock induced increased production of LOOHs in the gut, liver, and lungs (P < .001), whereas the production of O2− was also increased in the gut (P < .001), liver (P < .001), and, to a lesser extent, in the lungs (P < .05). The oxidative load of the kidneys, as estimated by both techniques, remained unaffected.ConclusionThe results of this new O2− assay were comparable with the results of the established LOOHs method, and this assay proved to be accurate and sensitive in the detection and quantification of O2− production in all organs tested. Thus, the proposed direct measurement of O2− in critically ill patients often facing in extremis situations could be used as a prognostic tool and as a method to evaluate therapeutic interventions in the setting of emergency medicine.