title: Hibernation in black bears: independence of metabolic suppression from body temperature.
abstract: Black bears hibernate for 5 to 7 months a year and, during this time, do not eat, drink, urinate, or defecate. We measured metabolic rate and body temperature in hibernating black bears and found that they suppress metabolism to 25% of basal rates while regulating body temperature from 30° to 36°C, in multiday cycles. Heart rates were reduced from 55 to as few as 9 beats per minute, with profound sinus arrhythmia. After returning to normal body temperature and emerging from dens, bears maintained a reduced metabolic rate for up to 3 weeks. The pronounced reduction and delayed recovery of metabolic rate in hibernating bears suggest that the majority of metabolic suppression during hibernation is independent of lowered body temperature.
authors.affiliation: Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA. otoien@alaska.edu
authors.forename: Øivind
authors.initials: Ø
authors.lastname: Tøien
authors.forename: John
authors.initials: J
authors.lastname: Blake
authors.forename: Dale M
authors.initials: DM
authors.lastname: Edgar
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Grahn
authors.forename: H Craig
authors.initials: HC
authors.lastname: Heller
authors.forename: Brian M
authors.initials: BM
authors.lastname: Barnes
mesh_terms: D000818:Animals; D001481:Basal Metabolism; D001831:Body Temperature; D004734:Energy Metabolism; D005260:Female; D006339:Heart Rate; D006605:Hibernation; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D013997:Time Factors; D001503:Ursidae / Q000378:metabolism / Q000502:physiology*