The superoxide anion radical (Of) produced in the alkaline dimethyl sulfoxide (DMSO) system was directly measured by electron paramagnetic resonance (EPR) at low temperature. This reaction was used as a model system for generating O2-. Astragalus membranaceus, Codonopsis pilousla, Paeonia laetiflora, Angelica sincnsis and Sophora flavescens, traditional natural medicines which have the effect of delaying anility, were added into the model system to observe their intensifying or inhibiting effect on EPR signals of O2. These results suggest that these traditional natural medicines have the mostly eliminating effect on Of produced in the alkaline DMSO system.

The effects of qi-tonics and blood-activating decoction on acute myocardial infarction and ischemia-reperfusion induced arrhythmias were studied in anaesthetized open chest SD rats. Three days before coronary artery occlusion, the qi-tonics and blood-activating decoction was perfused into the stomach of the rats in the experimental group (10 ml/kg weight) once a day, and 4d later, the coronary artery was occluded in anaesthetized open chest rats. The results demonstrated that qi-tonics and blood-activating decoction could reduce significantly the incidence and severity of arrhythmias caused by myocardial infarction and ischemia-reperfusion. The qi-tonics and blood-activating decoction could decrease the amount of the superoxide anion radicals (O2-) produced in the alkaline dimethyl sulfoxide (DMSO) system measured by electron paramagnetic resonance (EPR) at low temperature. The effect of qi-tonics and blood-activating decoction on O2-may be one of the mechanisms for its antiarrhythmic effect during reperfusion.