Abstract 11103: Reduced Expression of Electron Transport Proteins in Isolated Heart Mitochondria from Hibernating Versus Late Ischemic Preconditioned Hearts
Background: Maximal oxygen consumption is lower in hibernating hearts compared with ischemic preconditioned (IP) hearts and the difference may be explained in part by a down-regulation of protein expression within the electron transport chain (ETC) of hibernating mitochondria.
Methods: Ischemic preconditioning in the Second Window of Protection (SWOP) was induced in 7 pigs by ten cycles of 2-minute balloon inflations in the LAD artery separated by 2 minutes reperfusion. Hearts were extracted 24 hours later. Hibernating myocardium was induced by placing a constrictor around the LAD artery of 7 juvenile pigs and hearts were extracted 12 weeks later. Mitochondria were isolated from the LAD region by differential centrifugation and purity of the fraction was confirmed by detection of Prohibitin and analysis of the respiratory control index with an oxygen probe. Differential protein expression was compared using iTRAQ mass spectrometry technology for identification and relative quantification of mitochondrial proteins. Comparisons were made with mitochondria from SHAM hearts by Student's t-test and Bonferroni correction.
Results: A total of 243 mitochondrial proteins were identified and quantified in SWOP tissue and 3 ETC proteins were increased relative to SHAMs. The content of these proteins were analyzed in the Hibernating hearts and their relative abundance was expressed as a ratio to SHAM hearts. As shown, Complex IV (Cytochrome c oxidase), Complex V (ATPase) and NAD(P) transhydrogenase were higher in IP SWOP hearts and lower in Hibernating hearts compared with SHAM hearts.
Conclusions: When compared with SHAM hearts, expression of key ETC mitochondrial proteins is higher in ischemic preconditioned SWOP hearts and lower in Hibernating hearts. These differences in relative protein abundance may contribute in part, to the differences in maximal myocardial oxygen consumption that is known to be lower in hibernating compared with preconditioned hearts.
- Ischemic heart disease
- Energy metabolism
- Mitochondrial energetics, heart failure, arrhythmias
- © 2011 by American Heart Association, Inc.