Abstract: The kinetic changes of free radical generation in myocardial ischemia-reperfusion of rat and guinea pig were studied by means of spin trapping-ESR technique. The results indicated that not only the hydroxyl radical°OH, but also the carbon centered radical R°, as well as the alkyloxyl radical RO° were formed in reoxygenation processes, and the°OH radicals always were in majority. An interesting fact was first discovered in our experiments that the signal intensity of°OH radicals in reoxygenation processes increased constantly with time to a maximum and then slowly decayed almost to zero, a kinetics curve of change processes in test samples at different time-points was drawn. Up to date, this kinetic phenomena has not been reported yet in literatures. The kinetics equations for increasing and decreasing processes of hydroxyl free radicals were established respectively. The formation and change of free radicals might be described approximately by degenerate branching chain reaction scheme.

Key words: Ischemia-reperfusion, Free radical, Kinetics, ESR