Comparison of postasphyxial resuscitation with 100% and 21% oxygen on cortical oxygen pressure and striatal dopamine metabolism in newborn piglets

J Neurochem. 1995 Jan;64(1):292-8. doi: 10.1046/j.1471-4159.1995.64010292.x.

Abstract

The present study tests the hypothesis that ventilation with 100% O2 during recovery from asphyxia leads to greater disturbance in brain function, as measured by dopamine metabolism, than does ventilation with 21% oxygen. This hypothesis was tested using mechanically ventilated, anesthetized newborn piglets as an animal model. Cortical oxygen pressure was measured by the oxygen-dependent quenching of phosphorescence, striatal blood flow by laser Doppler, and the extra-cellular levels of dopamine and its metabolites by in vivo microdialysis. After establishment of a baseline, both the fraction of inspired oxygen (FiO2) and the ventilator rate were reduced in a stepwise fashion every 20 min over a 1-h period. For the subsequent 2-h recovery, the animals were randomized to breathing 21 or 100% oxygen. It was observed that during asphyxia cortical oxygen pressure decreased from 36 to 7 torr, extracellular dopamine increased 8,300%, and dihydroxyphenylacetic acid and homovanillic acid decreased by 65 and 60%, respectively, compared with controls. During reoxygenation after asphyxia, cortical oxygen pressure was significantly higher in the piglets ventilated with 100% oxygen than in those ventilated with 21% oxygen (19 vs. 11 torr). During the first hour of reoxygenation, extracellular dopamine levels decreased to approximately 200% of control in the 21% oxygen group, whereas these levels were still much higher in the 100% oxygen group (approximately 500% of control). After approximately 2 h of reoxygenation, there was a secondary increase in extracellular dopamine to approximately 750 and approximately 3,000% of baseline for the animals ventilated with 21 and 100%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn / metabolism*
  • Asphyxia / metabolism
  • Asphyxia / therapy*
  • Corpus Striatum / blood supply
  • Corpus Striatum / cytology
  • Corpus Striatum / metabolism*
  • Dopamine / metabolism*
  • Dose-Response Relationship, Drug
  • Oxygen / analysis
  • Oxygen / metabolism
  • Oxygen / pharmacology*
  • Regional Blood Flow / physiology
  • Resuscitation / methods*
  • Swine / metabolism*
  • Time Factors

Substances

  • Oxygen
  • Dopamine