Cardioprotective effects of urea and urea-derivatives (3 mM) against the electrolysis (10 mA, 1 min) induced oxidative stress on isolated rat heart. TU, thiourea; HU, Hydroxyurea; 1,1-DMU, 1,1-dimethylurea; 1,3-DMU, 1.3-dimethylurea; KH, Krebs-Henseleit buffer (n=4 for each group. *P>0.05 vs control).