Sildenafil after cardiac arrest and infarction; an experimental rat model

Objectives. Resuscitation after cardiac arrest may lead to ischemia-reperfusion injury and infarction. We evaluated whether Sildenafil, a phosphodiesterase-5 inhibitor, has an impact on recovery after cardiac arrest in a rat cardiac transplantation model. Design. Sixty-one Fischer344 rats underwent syngeneic heterotopic cardiac transplantation after ischemia and ligation of the left anterior coronary artery of the heart to yield myocardial infarction (IRI + MI). Of these, 22 rats received subcutaneously injected Sildenafil (1 mg/kg/day) (IRI + MI + S). Twenty-three additional grafted animals with transplantation only served as controls with ischemia reperfusion injury (IRI). After 2 days, immunohistochemistry for eNOS, and RT-PCR for iNOS and Aquaporin-7 were performed after graft harvesting and histology. Results. Two days after transplantation, remote intramyocardial arteries were more preserved in IRI + MI + S as compared with IRI + MI and IRI (0.74 +/- 0.14, 0.56 +/- 0.23 and 0.55 +/- 0.22, PSU, p < 0.05, respectively). Decreased eNOS staining confirmed the presence of developing infarction in IRI + MI and IRI + MI + S. The expression of iNOS was significantly lower during IRI + MI + S as compared with IRI + MI (0.02 +/- 0.01 and 1.02 +/- 0.02, FC, p < 0.05). Conclusions. Administered at the onset of reperfusion and developing infarction, Sildenafil has an impact on myocardial recovery after cardiac arrest and ischemia.