Correlating Cardiac Action Potentials with Metabolic Markers during Acute Cardiac Ischemia in Rabbit Hearts Public Deposited

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  • March 20, 2019
  • Kimball, Jeremiah
    • Affiliation: School of Medicine, UNC/NCSU Joint Department of Biomedical Engineering
  • We have developed the first system, to our knowledge, that simultaneously measures 31P nuclear magnetic resonance (NMR) and optical action potentials (APs) in order to determine the dynamic relationship between certain metabolic markers and AP morphology during acute ischemia in rabbit hearts. Our system utilizes a ratiometric optical technique with transmembrane voltage-sensitive dye, di-4-ANEPPS, to measure APs with no pharmalogical motion inhibition. Fiber optics measure APs by passing light to and from the heart within an NMR magnet. 31P NMR measurements verified the stoichiometric relationship between inorganic phosphate and phosphocreatine; as phosphocreatine levels decrease, inorganic phosphate levels increase. During acute ischemia, intracellular pH levels remained constant and ;-ATP levels decreased 22.4%. Simultaneous optical measurements show reductions in AP amplitude (-83.3%) and heart rate (-56.6%). AP duration increased (+875%), implicating other possible factors. These findings demonstrate a real-time correlation between ischemic depletion of high-energy phosphagens, and decreased AP amplitude and duration.
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  • Knisley, Stephen Bruce
  • Open access

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