Sirtuin 1 (SIRT1) activation mediates sildenafil induced delayed cardioprotection against ischemia-reperfusion injury in mice

It has been well documented that phosphodiesterase-5 inhibitor, sildenafil (SIL) protects against myocardial ischemia/reperfusion (I-R) injury. SIRT1 is part of the class III Sirtuin family of histone deacetylases that deacetylates proteins involved in cellular stress response including those related to I-R injury. We tested the hypothesis that SIL-induced cardioprotection may be mediated through activation of SIRT1. Adult male ICR mice were treated with SIL (0.7 mg/kg, i.p.), Resveratrol (RSV, 5 mg/kg, a putative activator of SIRT1 used as the positive control), or saline (0.2 mL). The hearts were harvested 24 hours later and homogenized for SIRT1 activity analysis. Both SIL- and RSV-treated mice had increased cardiac SIRT1 activity (P