The existing evidence support the view that oxidative stress may play a crucial role in cardiac and vascular abnormalities in different types of cardiovascular diseases and that the antioxidant therapy may prove beneficial in combating these problems.

In view of the critical role of sarcoplasmic reticular (SR) Ca2+ release and the Ca2+ pump in cardiac contraction-relaxation, this study was undertaken to assess the status of SR function, protein content, and gene expression in isolated rat hearts subjected to global ischemia for 30 min followed by 60 min of reperfusion (I/R). Attenuated recovery of contractile function in the I/R hearts was associated with reduced SR Ca2+ uptake, Ca2+ release, and ryanodine-binding activities. mRNA levels and protein contents for SR Ca2+ pump ATPase and Ca2+ release channels were markedly depressed in the I/R hearts. Perfusion of hearts with superoxide dismutase plus catalase, well-known scavengers of oxyradicals, prevented the I/R-induced alterations in cardiac function and partially prevented SR Ca2+transport activities and mRNA abundance. In hearts perfused with xanthine plus xanthine oxidase or H2O2, changes similar to those in the I/R hearts were observed. These results indicate that oxyradicals may participate in depressing the SR Ca2+ handling and gene expression in the I/R heart. It is suggested that treatment of hearts with antioxidants may improve the recovery of cardiac function by preserving the SR function and partially protecting the SR gene expression.