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Investigating Cardiac Metabolism in the Isolated Perfused Mouse Heart with Hyperpolarized [1-13C]Pyruvate and 13C/31P NMR Spectroscopy
Published on: April 21, 2023
Pyruvate prevents cardiac dysfunction and AMP-activated protein kinase activation by hydrogen peroxide in isolated
Hernando Leon1, Laura L Atkinson, Jolanta Sawicka
1Cardiovascular Reserach Group, Department of Pediatrics, University of Alberta, Edmonton, Canada.
Abstract:
Ischemia-reperfusion injury in the heart results in enhanced production of H2O2 and activation of AMP-activated protein kinase (AMPK). Since mutations in AMPK result in cardiovascular dysfunction, we investigated whether the activation of AMPK mediates the H2O2-induced reduction in cardiac mechanical function. Isolated working rat hearts were perfused at 37 degrees C with Krebs-Henseleit solution. Following a 20-minute equilibration period, a single bolus of H2O2 (300 micromol/L) was added and the hearts were perfused for an additional 5 min. H2O2 induced a dramatic and progressive reduction in cardiac function. This was accompanied by rapid and significant activation of AMPK, an increase in Thr-172 phosphorylation of AMPK, and an increase in the creatine to phosphocreatine (Cr/PCr) ratio. Addition of pyruvate (5 mmol/L) to the perfusate prevented the H2O2-mediated reduction in cardiac mechanical dysfunction, activation of myocardial AMPK activity, increase in AMPK phosphorylation and the increase in the Cr/PCr ratio. Hearts challenged with H2O2 (300 micromol/L) in presence of either AMPK inhibitor Compound C (10 micromol/L) or its vehicle (dimethyl sulfoxide (DMSO), 0.1%) showed reduced impairment in cardiac mechanical function. Compound C but not its vehicle significantly inhibited myocardial AMPK activity. Thus, H2O2 induces cardiac dysfunction via both AMPK-dependent and independent mechanisms.
Insights
Hydrogen peroxide (H2O2) impairs heart function by activating AMP-activated protein kinase (AMPK). Pyruvate or AMPK inhibition partially protects against this H2O2-induced cardiac dysfunction, suggesting dual mechanisms.
Area of Science:
- Cardiovascular Physiology
- Biochemistry
- Cellular Signaling
Background:
- Ischemia-reperfusion injury (IRI) in the heart elevates hydrogen peroxide (H2O2) and activates AMP-activated protein kinase (AMPK).
- AMPK dysfunction is linked to cardiovascular issues, prompting investigation into its role in H2O2-induced cardiac impairment.
Purpose of the Study:
- To determine if AMPK activation mediates the reduction in cardiac mechanical function caused by H2O2.
- To elucidate the mechanisms underlying H2O2-induced cardiac dysfunction.
Main Methods:
- Isolated working rat hearts were perfused with Krebs-Henseleit solution.
- Hearts were exposed to hydrogen peroxide (H2O2) with or without pyruvate or the AMPK inhibitor Compound C.
- Cardiac function, AMPK activity, and phosphorylation were measured.
Main Results:
- H2O2 significantly reduced cardiac function, accompanied by increased AMPK activation and Thr-172 phosphorylation.
- Pyruvate administration prevented H2O2-induced cardiac dysfunction and AMPK activation.
- Compound C, an AMPK inhibitor, reduced H2O2-induced cardiac mechanical impairment, indicating AMPK-dependent and independent pathways.
Conclusions:
- H2O2 induces cardiac dysfunction through both AMPK-dependent and independent mechanisms.
- Targeting AMPK may offer therapeutic potential in mitigating H2O2-related cardiac injury.
