Necrostatin-5 limits infarct size in the isolated rat heart

Abstract

Background: Inhibition of ischemia-reperfusion-induced programmed cardiac myocyte death has been considered as a promising therapeutic strategy for myocardial infarction. Necroptosis represents one of the recently discovered types of programmed cell death which could be manipulated by the pharmacological inhibitors – necrostatins. The aim of the present study was to study the effect of necroptosis inhibitors necrostatin-1 and -5 (Nec-1 and Nec-5, respectively) on myocardial infarct size in the isolated rat heart subjected to global ischemia-reperfusion. Methods: Male Wistar rats were anesthetized with pentobarbital sodium. The isolated Langendorff-perfused hearts were subjected to 30-min global ischemia and 120-min reperfusion. Infarct size was determined histochemically with triphenyltetrazolium chloride staining. Left ventricular pressures, heart rate, and coronary flow were monitored throughout the experiments. Nec-1 and -5 were dissolved in dimethyl sulfoxide (DMSO). The hearts were randomized into one of six groups: 1) controls (n = 8); 2) DMSO (n = 8) – the animals received intraperitoneal (i.p.) injection of vehicle 60 min prior to heart isolation; 3) intracoronary (i.c.) DMSO (n = 5) – the hearts were perfused with 64.7 mmol/L DMSO for 6.5 minutes before ischemia; 4) Nec-1 i.p. (n = 8) – Nec-1 was administered i.p. 60 min prior to heart isolation at a dose of 1.65 mg/kg; 5) Nec-5 i.p. (n = 13) – Nec-5 was administered in the same way as in the previous group at a dose of 2.46 mg/kg; 6) Nec-1 i.c. (n = 6) - the hearts were perfused with 44.5 mmol/L Nec-1 for 6.5 minutes before ischemia. Results: I.p. administration of DMSO caused a significant reduction in infarct size compared with controls (35.0±2.05 vs. 50.0±3.90%, respectively, p = 0.0042). I.p. injection of Nec-1 (20.9±3.02%) and Nec-5 (16.6±1.82%) further decreased infarct size in comparison with i.p. DMSO group (p = 0.0077 and 0.00048, respectively). I.c. administration of Nec-1 resulted in significant increase in the left ventricular systolic pressure (by 26.8±2.77% from baseline value). The positive inotropic effect of Nec-1 was limited to the period of drug administration. Nec-1 failed to reduce infarct size after preischemic i.c. administration (40.2±5.71%, vs. 50.8±2.11% in i.c. DMSO group, p = 0.175). Conclusion: This is the first study demonstrating the infarct-limiting effect of Nec-5. In addition, the positive inotropic effect of i.c. Nec-1 is described. Our data corroborate previous findings on the presence on infarct-limiting effect of Nec-1 in the setting of myocardial ischemia-reperfusion.