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Brain Vulnerability and Survival during Anoxia: Protective Strategies of Hypoxia-Resistant Vertebrates

  • Myron Rosenthal
  • Zi-Cai Feng
  • Thomas J. Sick
Part of the Advances in Behavioral Biology book series (ABBI, volume 35)

Summary

The extraordinary ability of turtle brain to survive anoxia has created interest in defining its protective strategies for reasons which include: a) to increase understanding of anaerobiosis; b) to define factors underlying mammalian brain vulnerability; and c) to examine potential applications of these strategies to cerebrovascular and metabolic diseases. A key to turtle brain survival during anoxia is continued cation transport for prolonged periods and avoidance of anoxic depolarization. When inspiration of oxygen was halted under experimental conditions, many mechanisms of compensation became apparent in turtle brain that supported the maintenance of ion homeostasis. Brain blood flow was continued or increased, and oxygen and creatine phosphate (PCr) stores offered some immediate protection. As PCr declined, turtle brain became increasingly reliant upon anaerobic glycolysis. In fact, transmembrane ion gradients were lost during ischemia or during anoxia with glycolytic inhibition (superfusion of brain with iodoacetate) and, in contrast to anoxia, these latter insults soon became irreversible. Evoked potential activity was inhibited by anoxia suggesting that excitability (synaptic transmission) had declined with what is likely a compensatory lowering of energy consumption. Also, stimulus-provoked increases in K o + were cleared less rapidly. K o + recovery rates were most retarded at low K o + values suggesting that high K o + “loads” either overcame the apparent compensatory decrease in K o + clearance rates or that an additional transport mechanism was activated to promote rapid K o + reaccumulation when stimulus-provoked K o + increments were high. This secondary process may not be present in mammalian brain and it may protect turtle brain against anoxic depolarization.

Keywords

Mammalian Brain Anaerobic Glycolysis Energy Failure Freshwater Turtle Brain Blood Flow 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • Myron Rosenthal
    • 1
    • 2
  • Zi-Cai Feng
    • 1
    • 2
  • Thomas J. Sick
    • 1
    • 2
  1. 1.Department of NeurologyUniversity of Miami School of MedicineMiamiUSA
  2. 2.Academy of Military Medical SciencesTianjinChina

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