Abstract 2: PTEN Inhibition Improves Cardiovascular Function and Energy Metabolism While Decreasing Inflammation After Mouse Cardiac Arrest

Abstract

Introduction: The survival kinase Akt mediates therapeutic hypothermia protection after mouse cardiac arrest (CA). This central kinase affects cardiovascular function, metabolism and inflammation. Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a primary phosphatase that negatively regulates Akt activity. We hypothesized that the PTEN inhibitor, VO-OHpic (VO), will mimic hypothermia protection by enhancing energy metabolism and cardiac function while reducing inflammation after CA. Methods: C57BL6 mice underwent 8 min of KCl-induced (0.08 mg/g) asystolic CA. VO (10 μg/kg) was administrated IP 30 min before CA. Neurologically intact survival at 72 h after CPR was measured and cardiac function was evaluated by Millar catheter. Blood lactate and glucose were assessed using colorimetric kits, and a cytokine panel using multiplex ELISA. Phosphorylation of Akt, GSK3β and phospholamban in heart and brain were studied by Western blot as markers of Akt activation. Heart cells isolated from 1-2-day old C57BL6 mice and exposed to 30 min ischemia and 90 min reperfusion were used to measure VO effects on contractile function in a cell model of cardiac stunning. Results: VO improved 72 hour survival (90% vs. 50%, p < 0.01). At 30 min after ROSC, VO significantly increased Dp/dt max (5123.4 ± 1026.9 mmHg/s vs. 4033.5 ± 622.4 mmHg/s, p<0.05), and ETCO2 (39.1 ± 2.8 vs. 35.3 ± 1.2 mmHg, p<0.05) with continued benefit seen at 2 hours. VO significantly increased lactate clearance by 4 hours demonstrated by decreased plasma lactate and glucose. The anti-inflammatory cytokine IL10 was increased while VO decreased the pro-inflammatory IL-1β. VO increased the phosphorylation of Akt (Thr308 and Ser473), p-GSK3β and the Akt target phospholamban. In mouse cardiomyocytes, VO (1 μM) improved the contractile velocity (54.6 ± 2.3 % vs. 33.3 ± 3.9 %, p < 0.05), increased total ATP content and the ratio of ATP/ADP during ischemia and enhanced L-type calcium channel recovery. Conclusions: PTEN inhibition improved neurologically intact survival after CA, with improved energy metabolism and cardiac function, and decreased inflammation. Use of PTEN inhibitors such as VO may be a novel strategy with or without cooling for treating the metabolic phase of cardiac arrest.