Abstract 276: TAT-PTEN9c Targets Heart Directly to Improve Survival From Cardiac Arrest

Abstract

Introduction: It is well established that hypothermia enhances cardiac arrest (CA) survival due, in part, to a mechanism of enhanced Akt activation. In this study we investigate whether the biosynthetic PTEN inhibitor (TAT-PTEN9c) provides therapeutic protection on survival due to direct effects on heart. Hypothesis: We hypothesized that TAT-PTEN9c interferes with endogenous PTEN binding at its cell membrane adaptor and leads to enhanced Akt activation, mouse survival and cardiac functional recovery. The improved CA survival is due in part to the improved contractile functional recovery of heart by TAT-PTEN9c. We also tested if the treatment targets the heart directly to enhanced recovery in isolated perfused rat heart after a period of global arrest. Methods: TAT-PTEN9c (7.5 mg/kg) was given intravenously (IV) after CA in mouse to determine protective effects of the treatment on survival and heart function. Western blot was used to determine the efficacy of TAT-PTEN9c for Akt activation. In the isolated rat heart, direct effect of treatment (1-10 μm) on cardiac function (HR, LVDP, RPP) were measured for 20 min following 20 min global ischemia. Results: In the mouse model of cardiac arrest, survival was significantly increased in the TAT-PTEN9c treated group compared to saline controls at 4 h (10/15, 67% vs. 6/15, 40%, P < 0.05) after CPR. TAT-PTEN9c improved MAP at both R30 min and R2h. The treated mice had increased Akt phosphorylation at R15 min in both heart and brain tissues with significantly decreased sorbitol content and reduced release of taurine and glutamate into blood, suggesting improved metabolic recovery and glucose utilization. For the isolated heart model, RPP was reduced by 25% for both TAT vehicle and non-treatment groups following arrest. With TAT-PTEN9c treatment, cardiac contractile function was completely recovered (pre-arrest RPP 29.1k+/- 4.8; post-arrest 28.0K +/- 5.0). Conclusion: TAT-PTEN9c enhances Akt activation and decrease glucose shunting to the polyol pathway in critical organs, preventing osmotic injury and early cardiovascular collapse and death. The improved survival by this treatment is in part due to its direct effect on heart functional recovery.