Importance of timing of magnesium administration: A study on the isolated ischemic-reperfused rat heart

The present study attempted to explore the antioxidant potential of magnesi um (2 and 10 mM) in the postischemic isolated rat heart. Magnesium demonstr ated a significant antioxidant effect, as deduced by thiobarbituric acid re active material and glutathione levels. However, this effect was evident on ly when magnesium was administered prior to ischemia but not when administe red during reperfusion. On the other hand, attenuation of calcium accumulat ion following reperfusion was noted in both treatment schedules and showed dose dependency when administered during reperfusion. Thus, the results of this study strongly suggests an antioxidant effect of magnesium which is di stinct from its calcium antagonising effects and it also stresses the criti cal role played by the time of administration of magnesium.