Abstract 20834: No Loss of Myocardial Infarct Size Reduction by Ischemic Preconditioning in P66shc Knockout Mice
Whereas high amounts of reactive oxygen species (ROS) contribute to cardiac damage following ischemia and reperfusion (I/R), low amounts function as trigger molecules in the cardioprotection by ischemic preconditioning (IPC). The hydrogen peroxide-generating protein p66shc resides in the cytosol but is translocated into the mitochondria upon various forms of stress. In the present study, we investigated the mitochondrial translocation of the protein upon a preconditioning stimulus and characterized the role of p66shc in I/R injury per se and the cardioprotection by IPC in vivo. Isolated wildtype mouse hearts were subjected to 30 min ischemia and 10 min reperfusion without and with IPC, or to time-matched normoxic perfusion. Subsequently, subsarcolemmal (SSM) and interfibrillar (IFM) mitochondria were isolated. Western Blot analysis showed that in SSM the p66shc content (in % of normoxic controls) was 137±10% after I/R (n=3, p<0.05) and was reduced to 107±6% (n=3, p=ns) after IPC. In IFM, p66shc increased to 148±11% after I/R (n=3, p<0.05) and was 109±8% after IPC. Wildtype and p66shc-knockout mice underwent 45 min ischemia and 120 min reperfusion without and with IPC in vivo. In wildtype mice, myocardial infarct size (in % of the area at risk) was 57.8±2.9% following I/R (n=9) and was reduced to 40.1±3.6% by IPC (n=9, p<0.05). In p66shc-knockout mice, similar infarct sizes were measured (I/R: 56.2±4.3%, n=11; IPC: 40±3.9%, n=14, p<0.05). Taken together, the reduced mitochondrial p66shc-translocation after IPC in vitro and the preserved infarct size reduction by IPC in p66shc knockout mice in vivo suggests that p66shc-derived ROS are not involved in the cardioprotection by IPC nor do they contribute to I/R injury per se.
Author Disclosures: K. Boengler: None. P. Ferdinandy: None. R. Schulz: None.
- © 2016 by American Heart Association, Inc.