title: Persistent regional downregulation in mitochondrial enzymes and upregulation of stress proteins in swine with chronic hibernating myocardium.
abstract: Hibernating myocardium is accompanied by a downregulation in energy utilization that prevents the immediate development of ischemia during stress at the expense of an attenuated level of regional contractile function. We used a discovery based proteomic approach to identify novel regional molecular adaptations responsible for this phenomenon in subendocardial samples from swine instrumented with a chronic LAD stenosis. After 3 months (n=8), hibernating myocardium was present as reflected by reduced resting LAD flow (0.75+/-0.14 versus 1.19+/-0.14 mL x min(-1) x g(-1) in remote) and wall thickening (1.93+/-0.46 mm versus 5.46+/-0.41 mm in remote, P<0.05). Regionally altered proteins were quantified with 2D Differential-in-Gel Electrophoresis (2D-DIGE) using normal myocardium as a reference with identification of candidates using MALDI-TOF mass spectrometry. Hibernating myocardium developed a significant downregulation of many mitochondrial proteins and an upregulation of stress proteins. Of particular note, the major entry points to oxidative metabolism (eg, pyruvate dehydrogenase complex and Acyl-CoA dehydrogenase) and enzymes involved in electron transport (eg, complexes I, III, and V) were reduced (P<0.05). Multiple subunits within an enzyme complex frequently showed a concordant downregulation in abundance leading to an amplification of their cumulative effects on activity (eg, "total" LAD PDC activity was 21.9+/-3.1 versus 42.8+/-1.9 mU, P<0.05). After 5-months (n=10), changes in mitochondrial and stress proteins persisted whereas cytoskeletal proteins (eg, desmin and vimentin) normalized. These data indicate that the proteomic phenotype of hibernating myocardium is dynamic and has similarities to global changes in energy substrate metabolism and function in the advanced failing heart. These proteomic changes may limit oxidative injury and apoptosis and impact functional recovery after revascularization.
authors.affiliation: VA WNY Health Care System, University at Buffalo, Buffalo, NY, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Page
authors.forename: Rebeccah
authors.initials: R
authors.lastname: Young
authors.forename: Vijay
authors.initials: V
authors.lastname: Iyer
authors.forename: Gen
authors.initials: G
authors.lastname: Suzuki
authors.forename: Maciej
authors.initials: M
authors.lastname: Lis
authors.forename: Lioubov
authors.initials: L
authors.lastname: Korotchkina
authors.forename: Mulchand S
authors.initials: MS
authors.lastname: Patel
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Blumenthal
authors.forename: James A
authors.initials: JA
authors.lastname: Fallavollita
authors.forename: John M
authors.initials: JM
authors.lastname: Canty
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000818:Animals; D002908:Chronic Disease; D004195:Disease Models, Animal; D015536:Down-Regulation; D004734:Energy Metabolism / Q000235:genetics*; D004798:Enzymes; D005786:Gene Expression Regulation / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic; D024101:Mitochondrial Proteins; D017682:Myocardial Stunning / Q000235:genetics*; D011506:Proteins / Q000032:analysis* / Q000235:genetics; D040901:Proteomics / Q000379:methods*; D013312:Stress, Physiological / Q000235:genetics*; D013552:Swine; D015854:Up-Regulation
chemical_list: D004798:Enzymes; D024101:Mitochondrial Proteins; D011506:Proteins