Extracellular pH and suppression of electrical activity during anoxia in turtle and rat brain

Z. C. Feng, T. J. Sick, M. Rosenthal

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

To evaluate the contribution of extracellular H+ activity toward depression of brain electrical activity during anoxia, extracellular pH (pH(e)) and field potentials were measured in turtle and rat olfactory bulbs with ion-selective microelectodes. This study tests the hypothesis that unique regulation of pH(e) contributes to the remarkable tolerance of turtle brain to prolonged anoxia. Hypercapnea (20% CO2 ventilation) depressed olfactory bulb evoked potentials 25-30% in both rat and turtle. During anoxia, evoked potentials were completely abolished within 1 min in rat olfactory bulb but decreased to only 40% of control after 4 h in the turtle despite similar changes in brain pH(e). Anoxia-induced acidification of turtle brain was exacerbated by hypercapnea and was attenuated by hypocapnea or by hypocapnea plus intravenous infusion of sodium bicarbonate. However, these manipulations of pH(e) during anoxia in turtle brain had little effect on depression of evoked potentials. We conclude that energy failure, rather than extracellular acidification, is the major contributor toward suppression of electrical activity in mammalian brain and that preservation of energy balance, rather than unique pH regulation, is responsible for protection of turtle brain during anoxia.

Original languageEnglish (US)
Pages (from-to)R205-R210
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume258
Issue number1 27-1
DOIs
StatePublished - 1990

Keywords

  • Carbon dioxide
  • Evoked potentials
  • Hydrogen ion
  • Olfactory bulb

ASJC Scopus subject areas

  • Physiology

Fingerprint Dive into the research topics of 'Extracellular pH and suppression of electrical activity during anoxia in turtle and rat brain'. Together they form a unique fingerprint.

  • Cite this