Enhanced cardioprotection against ischemia-reperfusion injury with combining sildenafil with low-dose atorvastatin

Purpose: Both ATV and SL reduce myocardial infarct size (IS) by enhancing expression and activity of NOS isoforms. We investigated whether atorvastatin (ATV) and sildenafil (SL) have synergistic effects on myocardial infarct size (IS) reduction and enhancing nitric oxide synthase (NOS) expression. Method: Rats were randomized to nine groups: ATV-1 (1 mg/kg/d); ATV-10 (10 mg/kg/d); SL-0.7 (0.7 mg/kg); SL-1 (1 mg/kg); ATV-1 + SL-0.7; water alone (controls); 1400W (iNOS inhibitor; I mg/kg); ATV-10 + 1400W; and ATV-1 + SL-0.7 + 1400W. ATV was administered orally for 3 days. SL was administered intraperitoneally 18 h before surgery and 1400W intravenously 15 min before surgery. Rats either underwent 30 min ischemia-4 h reperfusion or the hearts were explanted for immunoblotting and enzyme activity tests without being exposed to ischemia. Results: IS (% risk area, mean +/- SEM) was smaller in the ATV-10 (13 +/- 1%), SL-1 (11 +/- 2%), SL-0.7 (18 +/- 2%) and ATV-1 + SL-0.7 (9 + 1%) groups as compared with controls (34 +/- 3%; P < 0.001), whereas ATV-1 had no effect (29 2%). ATV-1 + SL-0.7 (9 1%) reduced IS more than SL-0.7 alone (p = 0.012). 1400W abrogated the protective effect of ATV-10 (35 3%) and ATV-1 + SL-0.7 (34 1%). SL-0.7 and ATV-10 increased phospborylated endothelial (Pc-NOS; 210 +/- 2.5% and 220 +/- 8%) and inducible (iNOS; 151 1% and 154 1%) NOS expression, whereas ATV-1 did not. These changes were significantly enhanced by ATV-1 + SL-0.7 (P-eNOS, 256 2%, iNOS 195 1%). SL-1 increased P-eNOS (311 +/- 22%) and MOS (185 +/- 1%) concentrations. Conclusions: Combining low-dose ATV with SL augments the IS limiting effects through enhanced P-eNOS and iNOS expression.