Abstract 11313: Expression of Mitochondrial Fusion Proteins is Increased Within Hibernating Myocardium Following CABG
Background: We have shown that expression of mitochondrial electron transport proteins is reduced 4 weeks following bypass surgery (CABG). In this study, we tested whether the expression of mitochondrial fusion proteins (Opa1) and mitofusins (Mfn 1&2), as an indicator of early recovery of the mitochondrial proteome, is increased post-CABG.
Methods: Nine pigs underwent placement of a constrictor on the LAD artery and had reduced function at 12 weeks. Four pigs underwent off-pump revascularization with a left internal mammary artery graft beyond the LAD stenosis (+CABG). Patent grafts were confirmed by CTA post-CABG. Five hibernating pigs without CABG served as comparisons (-CABG). Data were compared to 5 SHAM-operated controls (Con) without LAD constrictor. Prior to sacrifice, blood flows by μspheres were determined during dobutamine (40 μg/kg/min). Post-sacrifice, the content of mitochondrial fusion proteins and nuclear-bound PGC1α was determined by westerns.
Results: In the +CABG Group, blood flows during dobutamine were lower than Control (2.5±0.2 vs 3.5±0.2 ml/min/g; P<0.05), suggesting incomplete recovery at high work. Expression of fusion proteins and PGC1α signaling (See Figures) was increased in the +CABG Group however, indicating early recovery of the mitochondrial proteome.
Conclusion: Although oxygen consumption at higher work states is sub-maximal in hibernating hearts at 4-weeks post-CABG, expression of mitochondrial fusion proteins and PGC1α signaling are enhanced. These changes suggest that a process of mitochondrial fusion in hibernating hearts occurs early post-CABG, and may signal a process to support higher energetic states at a later time.
Author Disclosures: E.K. Long: None. C.T. Holley: None. C.M. Duffy: None. T.A. Butterick: None. H.B. Ward: None. E.O. McFalls: None. R.F. Kelly: None.
- © 2014 by American Heart Association, Inc.