Impaired myofibrillar energetics and oxidative injury during human atrial fibrillation

Michael J. Mihm, Fushun Yu, Cynthia A. Carnes, Peter J. Reiser, Patrick M. McCarthy, David R. Van Wagoner, John Anthony Bauer*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

531 Scopus citations

Abstract

Background - Atrial fibrillation (AF) is associated with severe contractile dysfunction and structural and electrophysiological remodeling. Mechanisms responsible for impaired contractility are undefined, and current therapies do not address this dysfunction. We have found that myofibrillar creatine kinase (MM-CK), an important controller of myocyte contractility, is highly sensitive to oxidative injury, and we hypothesized that increased oxidative stress and energetic impairment during AF could contribute to contractile dysfunction. Methods and Results - Right atrial appendages were obtained from AF patients undergoing the Maze procedure and from control patients who were in normal sinus rhythm and undergoing cardiac surgery. MM-CK activity was reduced in AF patients compared with controls (25.4±3.4 versus 18.2±3.8 μmol/mg of myofibrillar protein per minute; control versus AF; P<0.05). No reduction in total CK activity or myosin ATPase activity was detected. This selective reduction in MM-CK activity was associated with increased relative expression of the β-myosin isoform (25±6 versus 63±5%β, CTRL versus AF; P<0.05). Western blotting of AF myofibrillar isolates demonstrated no changes in protein composition but showed increased prevalence of protein oxidation as detected by Western blotting for 3-nitrotyrosine (peroxynitrite biomarker) and protein carbonyls (hydroxyl radical biomarker; P<0.05). Patterns of these oxidative markers were distinct, which suggests discrete chemical events and differential protein vulnerabilities in vivo. MM-CK inhibition was statistically correlated to extent of nitration (P<0.01) but not to carbonyl presence. Conclusions - The present results provide novel evidence of oxidative damage in human AF that altered myofibrillar energetics may contribute to atrial contractile dysfunction and that protein nitration may be an important participant in this condition.

Original languageEnglish (US)
Pages (from-to)174-180
Number of pages7
JournalCirculation
Volume104
Issue number2
DOIs
StatePublished - Jul 10 2001

Keywords

  • 3-Nitrotyrosine
  • Arrythmia
  • Contractility
  • Creatine kinase
  • Nitric oxide

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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