Novel cardiac protective effects of urea: from shark to rat

1 This study was carried out to investigate novel cardioprotective effects of urea and the underlying mechanisms. The cardiac functions under oxidativ e stress were evaluated using Langendorff perfused isolated heart. 2 Isolated dogfish shark hearts tolerated the oxidative stress generated by electrolysis (10 mA, min) of the perfusion solution (n=4), and also showed normal cardiac functions during postischaemia reperfusion (n = 4). The hig h concentration of urea (350 mM) in the heart perfusate was indispensable f or maintaining the normal cardiac functions of the shark heart. 3 Urea at 3-300 mM (n=4 for each group) protected the isolated rat heart ag ainst both electrolysis-induced heart damage and post-ischaemia reperfusion -induced cardiac injury. 4 A concentration-dependent scavenging effect of urea (3-300 mM, n=4 for ea ch group) against electrolysis-induced reactive oxygen species was also dem onstrated ill vitro. 5 Urea derivatives as hydroxyurea, dimethylurea, and thiourea had antioxida nt cardioprotective effect against the electrolysis-induced cardiac dysfunc tion of rat heart, but were not as effective as urea in suppressing the pos t-ischaemia reperfusion injury. 6 Our results suggest that urea and its derivatives are potential antioxida nt cardioprotective agents against oxidative stress-induced myocardium dama ge including the post-ischaemia reperfusion-induced injury.