Abstract 142: Combined Therapy with Polyethylene Glycol-20k and MCC950 Preserves Post-resuscitation Myocardial Mitochondrial Function in a Rat Model of Cardiac Arrest and Cardiopulmonary Resuscitation

Abstract

Introduction: Mitochondrial dysfunction from global ischemic-reperfusion (I/R) injury is a major contributor to post-resuscitation myocardial dysfunction. Polyethylene Glycol-20k (PEG-20k) shortens the no-flow phenomenon and improves microcirculation while MCC950 selectively inhibits activation of the NLRP3-inflammasome ensuing pyroptosis. We evaluated the effect of combined therapy with PEG-20k and MCC950 on myocardial mitochondrial function as measured by electron transport chain complex respiration in a rat model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Methods: 30 Sprague-Dawley rats weighing between 450-550 g were randomized into five groups (n=6): (1) sham (S); (2) control (C); (3) PEG-20k (P); (4) MCC950 (M); (5) combined (P&M). Ventricular fibrillation (VF) was electrically induced and untreated for 6min, followed by 8min CPR. Resuscitation was attempted with a 4J defibrillation. 2mL P was infused over 2 min at the beginning of CPR, while M (10mg/kg) was administered intraperitoneal (IP) immediately after return of spontaneous circulation (ROSC). At ROSC 6hr, 100mg of heart was harvested, transferred directly into ice-cold K medium (1mL), and homogenized to obtain a 10% homogenate. Homogenates (50μL) were transferred to calibrated Oxygraph-2 chambers. Mitochondrial function was measured using high resolution respirometry. Oxygen flux was corrected and expressed by tissue wet weight, pmol/(min*mg). Data were analyzed by one-way analysis of variance (one-way ANOVA) followed by Tukey’s post hoc test for comparisons between multiple groups. Results: Complex I respiration in C was compromised at ROSC 6hr compared to S (564.0±160.0 vs 2729.5±339.5, p<0.001). As expected, P and M restored complex I respiration (1224.4±328.6, p<0.001) and (1804.4±293.1, p<0.01) compared to C. P&M further consolidated Complex I respiration function recovery (2527.6±145.5). Conclusion: Combined Therapy with PEG-20k and MCC950 preserves post-resuscitation myocardial mitochondrial function in a rat model of CA and CPR.