Abstract 200: Inhibition of Mitochondrial Permeability Transition Pore by Intralipid Protects the Late Pregnant Heart Against Ischemia Reperfusion Injury
Introduction: Recently, we found that late pregnant (LP) hearts have higher vulnerability to ischemia/reperfusion (I/R) injury compared to non-pregnant hearts. We also discovered that intralipid (ITLD), a safe clinically relevant compound, can protect the male mouse heart against I/R injury. Here we examined whether ITLD can protect LP hearts against I/R injury and if this protection is mediated by delaying the opening of mitochondrial permeability transition pore (mPTP).
Methods: Isolated LP mouse hearts were subjected to 20 min ischemia followed by reperfusion (40 or 10 min) with Krebs-Henseleit (CTRL), or 1% ITLD. For in-vivo experiments, the left anterior descending coronary artery of female rats was occluded for 45 min followed by 3 hr of reperfusion. One single bolus of PBS or 20% ITLD (5ml/kg) was applied through the femoral vein 5 min before reperfusion. Myocardial necrosis was assessed using TTC staining. Mitochondria were isolated to measure Calcium Resistance Capacity (CRC). Standard Western blot analysis, 2D-DIGE and mass spectrometry were performed. One way or two way ANOVA was used and p<0.05 considered significant. Data were expressed as mean± SEM and n=4–6 animals/group.
Results: ITLD treatment significantly improved postischemic cardiac function of LP mice (RPP=1614±438 in CTRL vs. 11556±784 mmHg*beats/min in ITLD) and reduced the infarct size (59.7±5.2% in CTRL mice to 15.2±0.8% in ITLD). Similar to ex-vivo, the infarct size was also significantly higher in LP (52.3±3.5%) compared to ITLD group (19.5±2.3%). ITLD treatment increased the phosphorylated levels of AKT and GSK-3b by 1.8 and 2.6 fold in LP, respectively. The opening of the mPTP was also delayed by ITLD treatment, as CRC increased from 1.8±0.07 uM/mg in CTRL to 2.9±0.12 uM/mg in ITLD. To identify the key signaling proteins that are involved in ITLD-induced cardioprotection, we performed 2D-DIGE and mass spectrometry. Most of the proteins that were differentially regulated by ITLD were in fact mitochondrial proteins such as voltage dependent anion channel (VDAC-2), which was downregulated by 28% with ITLD treatment. The downregulation of VDAC-2 was confirmed by Western blot analysis.
Conclusion: ITLD protects LP hearts against I/R injury by inhibiting the opening of the mPTP.
- © 2010 by American Heart Association, Inc.