PURPOSE: Necroptosis has been proposed as a mode of cell death that is a caspase-independent programmed necrosis. We investigated whether necroptosis is involved in myocardial ischemia-reperfusion injury in isolated guinea pig hearts and, if so, whether simultaneous inhibition of necroptosis and apoptosis confers enhanced cardioprotection.
METHODS: Isolated perfused guinea pig hearts were subjected to 30 min ischemia and 4 h reperfusion (control = CTL, n = 8). Necrostatin-1 (necroptosis inhibitor, 10 μM), Z-VAD (apoptosis inhibitor, 0.1 μM) and both inhibitors were administered starting 5 min before ischemia and during the initial 30 min of reperfusion (Nec, Z-VAD, Nec + Z-VAD; n = 8 each). Contractile recovery was monitored by left ventricular developed (LVDP) and end-diastolic (LVEDP) pressure. Infarct size was determined by triphenyltetrazolium chloride staining. Tissue samples were obtained after 4 h reperfusion to determine expression of receptor-interacting protein 1 (RIP1) and activated caspase 3 by Western blot analysis.
RESULTS: After reperfusion, Nec + Z-VAD had higher LVDP and lower LVEDP compared with CTL. Infarct size was reduced in Nec and Z-VAD compared with CTL. Combination of necroptosis and apoptosis inhibition further reduced infarct size. Expression of activated caspase 3 was not increased in Z-VAD and Nec + Z-VAD compared with Nec and CTL. Expression of RIP1 was preserved in Z-VAD and Nec + Z-VAD compared with CTL, suggesting RIP1-mediated necrosis is involved in myocardial ischemia-reperfusion injury.
CONCLUSION: Necroptosis is involved in myocardial ischemia-reperfusion injury, and simultaneous inhibition of necroptosis and apoptosis enhances the cardioprotective effect. These findings may provide a novel, additive strategy for cardioprotection in acute myocardial infarction.
Recommended CitationKoshinuma, Shizuka; Miyamae, Masami; Kaneda, Kazuhiro; Kotani, Junichiro; and Figueredo, Vincent M., "Combination of necroptosis and apoptosis inhibition enhances cardioprotection against myocardial ischemia-reperfusion injury." (2013). Division of Cardiology Faculty Papers. Paper 31.