Mapping hypoxia-induced bioenergetic rearrangements and metabolic signaling by18O-assisted31P NMR and1H NMR spectroscopy

This study shows specific benefits stemming from the combined use of highresolution 31P and 1H NMR spectroscopy that accompanies 18O analysis

Darko Pucar

2003

Scholarcy highlights

  • Oxygen deficiency associated with hypoxic or ischemic stress in heart muscle disrupts mitochondrial oxidative phosphorylation compromising ATP production and associated ATPdependent cellular processes
  • In the well-oxygenated heart, transfer of high-energy phosphoryls between sites of ATP production and consumption is facilitated by the creatine kinase and adenylate kinase system, with creatine kinase phosphotransfer serving a dominant role
  • Reduction in the CK/AK flux ratio, from 6.5 ± 0.4 in normoxia to 0.8 ± 0.2 in hypoxia, indicates rearrangement in phosphotransfer signaling with adenylate kinase playing a major role in supporting heart energetics under hypoxic stress
  • 18O-assisted 31P NMR with 1H NMR analysis mapped the bioenergetic dynamics of the myocardium under hypoxic stress
  • While in normoxia the majority of high-energy phosphoryl transfer proceeds through the creatine kinase system with a relatively minor contribution by AK, under hypoxia the rapid decline in CK-mediated phosphotransfer was associated with an apparently adaptive up-regulation of AK-catalyzed flux, and the generation of adenosine monophosphate, inosine monophosphate and adenosine, molecules involved in cardioprotective signaling
  • 31P and 1H NMR spectral analysis revealed that scavenging of NADH and H+, by α-glycerophosphate dehydrogenase and lactate dehydrogenase, contributing to maintained glycolysis, which along with AK phosphotransfer supports cardiac bioenergetics under hypoxia
  • In a single experiment one can measure creatine kinase, adenylate kinase and glycolytic phosphotransfer fluxes, as well as ATP production, consumption and total turnover rates, providing a comprehensive analysis of dynamic alterations in the energetic system of an intact cell

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