Failure to detect free radicals in the isolated perfused rat heart

Oxygen free radicals have been indirectly implicated in reperfusion injury following ischemia in the isolated rabbit heart. The authors moved to detect free radicals in an isolated rat heart model as a prerequisite to studying its effects during ischemia and reperfusion. Several different spin trapping agents and electron paramagnetic resonance (EPR) spectroscopy were used to detect free radicals being generated during ischemia and reperfusion. The possible roles of ferrous iron and hydrogen peroxide generation in reperfusion injury were also investigated. No free radical "bursts" were detected with any of the spin traps used in this model during ischemia or reperfusion. Hydrogen peroxide and hydroxyl free radicals do not appear to be involved in tissue reperfusion injury. This study suggests that free radicals are not produced in clinically significant quantities under these conditions to account for ischemic myocardial damage.