Hypothermia and amiloride preserve energetics in a neonatal brain slice model

Nicola J Robertson, Kishore Bhakoo, Basant K Puri, A David Edwards, I Jane Cox

Research output: Contribution to journalArticlepeer-review

Abstract

A period of secondary energy failure consisting of a decline in phosphocreatine/inorganic phosphate (PCr/Pi), a rise in brain lactate, and alkaline intracellular pH (pH(i)) has been described in infants with neonatal encephalopathy. Strategies that ameliorate this energy failure may be neuroprotective. We hypothesized that a neonatal rat brain slice model undergoes a progressive decline in energetics, which can be ameliorated with hypothermia or amiloride. Interleaved phosphorus ((31)P) and proton ((1)H) magnetic resonance (MR) spectra were obtained from 350 microm neonatal rat brain slices over 8 h in a bicarbonate buffer at 37 degrees C and at 32 degrees C in 7- and 14-d models. (31)P MR spectra were obtained with amiloride in a bicarbonate-free buffer at 37 degrees C in the 14-d model. Findings were similar in 7- and 14-d models. In the 14-d model, there was a Pi doublet structure corresponding to alkaline pH(i) values of 7.50 +/- 0.02 and 7.21 +/- 0.04. Compared with the stabilized baseline of 100, at 5 h PCr/Pi was 65 +/- 6.3 and lactate/NAA was 187 +/- 3 at 37 degrees C, but PCr/Pi and lactate/NAA were not significantly different from baseline at 32 degrees C. Nucleotide triphosphate (NTP)/phosphomonoester (PME) was 0.93 +/- 0.23 at 37 degrees C and 1.81 +/- 0.21 at 32 degrees C at 5 h. With amiloride exposure in the 14-d model, baseline pH(i) values were 7.25 +/- 0.09 and 6.98 +/- 0.02 and NTP/PME was 1.81 +/- 0.05; these parameters were not significantly different at 5 h. Our interpretation of these findings is that the brain slice model underwent secondary energy failure, which was delayed with hypothermia or amiloride.

Original languageEnglish
Pages (from-to)288-96
Number of pages9
JournalPediatric Research
Volume58
Issue number2
DOIs
Publication statusPublished - Aug 2005

Keywords

  • Amiloride/therapeutic use
  • Animals
  • Animals, Newborn
  • Brain/metabolism
  • Brain Diseases/drug therapy
  • Energy Metabolism
  • Esters/chemistry
  • Female
  • Hydrogen-Ion Concentration
  • Hypothermia, Induced
  • Hypoxia, Brain
  • Lactates/chemistry
  • Magnetic Resonance Imaging
  • Magnetic Resonance Spectroscopy
  • Male
  • Phosphorus Isotopes
  • Rats
  • Temperature
  • Time Factors

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