Key result
During acute ischemia in rabbit hearts, gamma-ATP levels decreased by 22.4%, action potential amplitude decreased by 83.3%, and action potential duration increased by 875%.
Why the study?
The study was conducted to determine the dynamic relationship between metabolic markers and action potential morphology during acute ischemia using simultaneous 31P nuclear magnetic resonance and optical action potential measurements.
A novel system simultaneously measuring 31P NMR and optical action potentials demonstrates a real-time correlation between ischemic depletion of high-energy phosphagens and altered action potential morphology in rabbit hearts.
Answers are grounded in this paper and cite their sources.
No immediate clinical implications; extends preclinical correlation of ATP depletion with action potential changes in ischemia.
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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Jeremiah Kimball (2019) studied Acute cardiac ischemia. Acute cardiac ischemia vs. Pre-ischemia was evaluated on Changes in action potential amplitude, duration, and gamma-ATP levels. During acute ischemia in rabbit hearts, gamma-ATP levels decreased by 22.4%, action potential amplitude decreased by 83.3%, and action potential duration increased by 875%.
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