title: Skeletal Muscle Mitochondrial Content, Oxidative Capacity, and Mfn2 Expression Are Reduced in Older Patients With Heart Failure and Preserved Ejection Fraction and Are Related to Exercise Intolerance.
abstract: The aim of this study was to examine skeletal muscle mitochondria content, oxidative capacity, and the expression of key mitochondrial dynamics proteins in patients with heart failure with preserved ejection fraction (HFpEF), as well as to determine potential relationships with measures of exercise performance.
  
  
  
  Multiple lines of evidence indicate that severely reduced peak exercise oxygen uptake (peak VO2) in older patients with HFpEF is related to abnormal skeletal muscle oxygen utilization. Mitochondria are key regulators of skeletal muscle metabolism; however, little is known about how these organelles are affected in HFpEF.
  
  
  
  Both vastus lateralis skeletal muscle citrate synthase activity and the expression of porin and regulators of mitochondrial fusion were examined in older patients with HFpEF (n = 20) and healthy, age-matched control subjects (n = 17).
  
  
  
  Compared with age-matched healthy control subjects, mitochondrial content assessed by porin expression was 46% lower (p = 0.01), citrate synthase activity was 29% lower (p = 0.01), and Mfn2 (mitofusin 2) expression was 54% lower (p <0.001) in patients with HFpEF. Expression of porin was significantly positively correlated with both peak VO2 and 6-min walk distance (r = 0.48, p = 0.003 and r = 0.33, p = 0.05, respectively). Expression of Mfn2 was also significantly positively correlated with both peak VO2 and 6-min walk distance (r = 0.40, p = 0.02 and r = 0.37, p = 0.03 respectively).
  
  
  
  These findings suggest that skeletal muscle oxidative capacity, mitochondrial content, and mitochondrial fusion are abnormal in older patients with HFpEF and might contribute to their severe exercise intolerance.
authors.affiliation: Gerontology Section, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Anthony J A
authors.initials: AJ
authors.lastname: Molina
authors.affiliation: Gerontology Section, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Manish S
authors.initials: MS
authors.lastname: Bharadwaj
authors.affiliation: Gerontology Section, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Van Horn
authors.affiliation: Gerontology Section, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Nicklas
authors.affiliation: Gerontology Section, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Mary F
authors.initials: MF
authors.lastname: Lyles
authors.affiliation: Cardiology Section, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Joel
authors.initials: J
authors.lastname: Eggebeen
authors.affiliation: College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Haykowsky
authors.affiliation: Department of Exercise and Health Science, Wake Forest University, Winston-Salem, North Carolina.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Brubaker
authors.affiliation: Cardiology Section, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina. Electronic address: dkitzman@wakehealth.edu.
authors.forename: Dalane W
authors.initials: DW
authors.lastname: Kitzman
mesh_terms: D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D002950:Citrate (si)-Synthase / Q000378:metabolism; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D006333:Heart Failure / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008931:Mitochondria, Muscle / Q000378:metabolism*; D063154:Mitochondrial Dynamics; D024101:Mitochondrial Proteins / Q000378:metabolism*; D010101:Oxygen Consumption; D052097:Quadriceps Muscle / Q000378:metabolism* / Q000473:pathology; D013318:Stroke Volume; D050995:Voltage-Dependent Anion Channel 1 / Q000378:metabolism
chemical_list: D024101:Mitochondrial Proteins; C494762:VDAC1 protein, human; D050995:Voltage-Dependent Anion Channel 1; D002950:Citrate (si)-Synthase; D020558:GTP Phosphohydrolases; C470018:MFN2 protein, human
keywords: aging; exercise; heart failure; mitochondria; preserved ejection fraction; skeletal muscle