Abstract 15248: DhHP6 Protects the Heart From Ischemia-Reperfusion Injury by Preventing Mitochondrial Oxidative Damages via Inhibition of p66SHC Phosphorylation

Introduction: Increased mitochondrial (Mito) reactive oxygen species (ROS) generation is a major cause of cardiac ischemia/reperfusion (IR) injury. We previously reported that deuterohaemin-AlaHisThrValGluLys (DhHP6), a novel cell-permeable deuterated porphyrin peptide, extended lifespan and enhanced stress resistance in C. elegans at least in part via effects on Mito ROS generation. p66 SHC is an adaptor protein that regulates multiple pathways governing Mito redox state and ROS generation. Here we studied the effects of DhHP6 on phosphorylation and Mito translocation of p66 SHC , Mito oxidative stress, and cardiac function in mouse heart model of IR injury. Methods: Hearts (n=8 each) isolated from FVB mice were perfused in the Langendorf mode. Following the treatment with DhHP6 or vehicle for 20 min, hearts were subjected to global, no-flow normothermic ischemia (20 min) and reperfusion (30 min). Cardiac systolic and diastolic function indices were measured continuously. Whole protein lysate, cytosolic and Mito fractions were prepared to assess the phosphorylation and translocation of p66 SHC . Mito H 2 O 2 , malondialdehyde (MDA), protein carbonyls, and 8-hydroxy-2-deoxyguanosine (8HOdG) were measured to assess ROS generation and oxidative damage to lipids, proteins and DNA, respectively. Results: 10 μM DhHP6 significantly decreased the IR-induced phosphorylation of p66 SHC at serine 36 and its translocation to mitochondria. Consistently, DhHP6 reversed IR-induced increases in H 2 O 2 , MDA, protein carbonyls, and 8HOdG levels. Importantly, DhHP6 also significantly improved functional recovery after IR injury compared with vehicle (Figures). Conclusions: Our data indicate that DhHP6 protects the heart against IR injury in vitro at least in part by preventing Mito oxidative damage via mechanisms that are likely to include decreasing p66 SHC phosphorylation and Mito accumulation. Its potential to protect the heart against IR injury merits further study.