Microwave irradiation decreases ATP, increases free [Mg2+], and alters in vivo intracellular reactions in rat brain

Shireesh Srivastava, Yoshihiro Kashiwaya, Xuesong Chen, Jonathan D. Geiger, Robert Pawlosky, Richard L. Veech

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Rapid inactivation of metabolism is essential for accurately determining the concentrations of metabolic intermediates in the in vivo state. We compared a broad spectrum of energetic intermediate metabolites and neurotransmitters in brains obtained by microwave irradiation to those obtained by freeze blowing, the most rapid method of extracting and freezing rat brain. The concentrations of many intermediates, cytosolic free NAD(P)+/NAD(P)H ratios, as well as neurotransmitters were not affected by the microwave procedure. However, the brain concentrations of ATP were about 30% lower, whereas those of ADP, AMP, and GDP were higher in the microwave-irradiated compared with the freeze-blown brains. In addition, the hydrolysis of approximately 1 μmol/g of ATP, a major in vivo Mg2+-binding site, was related to approximately five-fold increase in free [Mg2+] (0.53 ± 0.07 mM in freeze blown vs. 2.91 mM ± 0.48 mM in microwaved brains), as determined from the ratio [citrate]/[isocitrate]. Consequently, many intracellular properties, such as the phosphorylation potential and the ΔG' of ATP hydrolysis were significantly altered in microwaved tissue. The determinations of some glycolytic and TCA cycle metabolites, the phosphorylation potential, and the ΔG' of ATP hydrolysis do not represent the in vivo state when using microwave-fixed brain tissue.

Original languageEnglish (US)
Pages (from-to)668-675
Number of pages8
JournalJournal of Neurochemistry
Volume123
Issue number5
DOIs
StatePublished - Dec 1 2012

Keywords

  • anoxic changes
  • biochemical thermodynamics
  • freeze blowing
  • intermediate metabolites
  • neurotransmitters
  • phosphorylation potential

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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