title: Freeze avoidance in a mammal: body temperatures below 0 degree C in an Arctic hibernator.
abstract: 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.
authors.affiliation: Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks 99775-0180.
authors.forename: B M
authors.initials: BM
authors.lastname: Barnes
mesh_terms: D000818:Animals; D021301:Antifreeze Proteins; D001110:Arctic Regions; D001143:Arousal; D001831:Body Temperature; D001833:Body Temperature Regulation; D005260:Female; D005615:Freezing; D006023:Glycoproteins / Q000032:analysis; D006605:Hibernation; D008297:Male; D012589:Sciuridae / Q000502:physiology*
chemical_list: D021301:Antifreeze Proteins; D006023:Glycoproteins