Freeze avoidance in a mammal: body temperatures below 0 degree C in an
Science. 244(4912):1593-5, 1989 Jun 30.
Hibernating arctic ground squirrels, Spermophilus parryii,
were able to adopt and spontaneously arouse from core body temperatures as
low as -2.9 degrees C without freezing. Abdominal body temperatures of ground
squirrels hibernating in outdoor burrows were recorded with
temperature-sensitive radiotransmitter implants. Body temperatures and soil
temperatures at hibernaculum depth reached average minima during February of
-1.9 degrees and -6 degrees C, respectively. Laboratory-housed ground
squirrels hibernating in ambient temperatures of -4.3 degrees C maintained
above 0 degree C thoracic temperatures but decreased colonic temperatures to
as low as -1.3 degrees C. Plasma sampled from animals with below 0 degree C
body temperatures had normal solute concentrations and showed no evidence of
containing antifreeze molecules.
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