Alterations to mitochondrial proteins initiated during myocardial ischemic preconditioning

Abstract

Cardiac muscle damage caused by ischemia and reperfusion (I/R) involves impairment of the contractile, electrophysiological, and energy producing systems of the heart. The mitochondria play a key role in cell survival and recovery of function. Protection against I/R injury afforded by myocardial ischemic preconditioning (IPC), initiated by a series of short sub-lethal ischemic events, is suggested to be linked to major changes in the mitochondria. The focus of this work is to characterize how IPC affects the mitochondrial proteome using multiple proteomic technologies. Mitochondria were enriched from isolated rabbit hearts subjected to 1 cycle of IPC (5I/5R), 2 cycles IPC (5I/5R+5I/5R) and constant perfusion (control), by differential centrifugation. To improve the resolution of the mitochondrial proteome, both gel based (2-dimensional gel electrophoresis and 1-dimensional gel electrophoresis with reverse phase liquid chromatography (LC)), and gel free (2-dimensional LC) methodologies, have been utilised prior to protein identification by mass spectrometry. By combining these techniques, there is improved coverage of the mitochondrial protein content as less than 10% proteome coverage occurs between all three methods. Changes have been observed to multiple proteins, including protein kinase C inhibitor-2 and the mitochondrial import inner membrane translocase. By complementing these techniques, there is improved coverage of the mitochondrial proteins. As such, the modifications to mitochondrial proteins in response to IPC, which aid in the conferred myocardial protection, are observed.