Abstract 15028: PTEN Inhibition Preserves Cardiomyocyte Contractility and Improves Murine Cardiac Arrest Survival
Introduction: Post-cardiac arrest myocardial stunning is often lethal in the first few hours after resuscitation. We previously reported this stunning is reversed by cooling via an Akt-dependent process in a mouse model of cardiac arrest. Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a primary phosphatase that negatively regulates Akt phosphorylation. We hypothesized that the PTEN inhibitor, VO-OHpic, preserves cardiomyocyte contraction and improves survival after ischemic arrest, affecting Akt targets related to contraction and energy.
Methods: Cardiomyocytes isolated from 1-2-day old C57BL6 mice were exposed to 30 min ischemia and 90 min reperfusion. To assesse contractile preservation, isoproterenol was added at the end of reperfusion. Contraction was measured by phase contract imaging and Matlab software. Akt activity and phosphorylation of Akt (p-Akt) and GSK3β (p-GSK3β), Serca2α were measured by immunoprecipitation and western blot. ATP content and ATP/ADP ratio were detected using a luciferase ATP assay kit. For cardiac arrest study, C57BL6 mice (n=20) underwent 8 min of KCl-induced (0.08 mg/g) asystolic cardiac arrest with prior treatment using VO-OHpic versus vehicle. Two hours after the return of spontaneous circulation, the animals were sutured and monitored for up to 72 hours. Neurological function was assessed.
Results: Cell contraction stopped within 2-5 min ischemia, restarted at 10 min reperfusion and returned to 33.3 % of baseline at 90 min reperfusion. VO-OHpic (1 µM) administered during reperfusion further recovered contraction (54.6 ± 2.3 % vs. 33.3 ± 3.9 %, p < 0.05) and preserved contractile function reflected by isoproterenol (10 µM) (77.5 ± 4.9 % vs. 47.6 ± 3.2 %, p < 0.05). At the end of 30 min ischemia, VO-OHpic augmented both Akt phosphorylation (Thr308 and Ser473) and activity, increased p-GSK3β and Serca2α. ATP content and ATP/ADP ratio were also raised. In mice, VO-OHpic (10 µg/kg, i.p), given 30 min prior to arrest, improved neurological function and 72 h survival (p < 0.05).
Conclusions: PTEN inhibition preserves cardiomyocyte contractility following ischemic arrest, increasing Akt-related p-GSK3β and Serca2α with improved ATP generation and survival.
- © 2012 by American Heart Association, Inc.