Pflügers Archiv

, Volume 344, Issue 4, pp 327–337 | Cite as

Effects of exposure to hot environments on total and regional blood flow in the brain and spinal cord of the sheep

  • J. R. S. Hales
Article

Summary

In conscious adult sheep, normal blood flow rate (ml 100 g−1 min−1) differed markedly in different regions of the brain and spinal cord. In mild heat stress there was no significant change in total or regional blood flow in the brain or spinal cord. In severe heat stress body temperature increased at a rate of approximately 2°C per hour, until a total change of approximately 2.4°C had occurred. Vigorous panting resulted in severe respiratory alkalosis. Brain and spinal cord blood flow declined to approximately 70% of control levels, the change being greatest in the pons and medulla oblongata and least in the cerebellum. It is suggested that a much greater fall in blood flow was prevented by a stimulatory effect of increased body temperature counteracting depressant effects of hypocapnia and possibly other factors. There does not appear to be any blood flow through arteriovenous anastomoses in the brain. Oxygen consumption by the cerebral hemispheres either remained unchanged or decreased slightly.

Key words

Brain Blood Flow Brain Oxygen Consumption Brain AVA's Hyperthermia Sheep Brain 

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Copyright information

© Springer-Verlag 1973

Authors and Affiliations

  • J. R. S. Hales
    • 1
  1. 1.Division of Animal Physiology, Ian Clunies Ross Animal Research Laboratory, ProspectC.S.I.R.O.Australia

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