Activity, blood temperature and brain temperature of free-ranging springbok |
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Authors: | Duncan Mitchell Shane K Maloney Helen P Laburn Michael H Knight Gernot Kuhnen Claus Jessen |
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Institution: | Department of Physiology, University of the Witwatersrand, Johannesburg, 2193, South Africa, ZA Scientific Services, Southern National Parks, Kimbereley, 8300, South Africa, ZA Physiologisches Institut, Justus-Liebig-Universit?t, D-35392 Giessen, Germany, Fax: +49-641/99-47239, e-mail: gernot.kuhnen@physiologie.med.uni-giessen.de, DE
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Abstract: | We used miniature data loggers to record temperature and activity in free-ranging springbok (Antidorcas marsupialis) naturally exposed to severe nocturnal cold and moderate diurnal heat. The animals were active throughout the day and night,
with short rests; the intensity of activity increased during daylight. Arterial blood temperature, averaged over many days,
exhibited a circadian rhythm with amplitude <1 °C, but with a wide range which resulted from sporadic rapid deviations of
body temperature. Peak blood temperature occurred after sunset. Environmental thermal loads had no detectable effect on blood
temperature, even though globe temperature varied by >10 °C from day to day and >20 °C within a day. Brain temperature increased
approximately linearly with blood temperature but with a slope <1, so that selective brain cooling tended to be activated
at high body temperature, but without a precise threshold for the onset of brain cooling. Low activity attenuated selective
brain cooling and high activity abolished it, even at high brain temperature. Our results support the concept that selective
brain cooling serves to modulate thermoregulation rather than to protect the brain against heat injury.
Accepted: 7 January 1997 |
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Keywords: | Selective brain cooling Exercise Environmental thermal load Body temperature Antelope |
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