Hibernation in arctic mammals. Kelly Drew Brian Barnes Institute of Arctic Biology arctic ground squirrel ( Urocitellus parryii )
Arctic ground squirrels supercool their body fluids during hibernation.
Two year record of core body temperature of a free- 314 female arctic ground squirrel living arctic ground squirrel in northern Alaska. 45 - 104 40 body temperature (°C) - 95 35 30 25 ( o F) 20 15 10 5 - 32 0 -5 8/1/98 12/1/98 4/1/99 8/1/99 12/1/99 4/1/00 Fall Winter Spring Summer Fall Winter Spring
Hibernating ground squirrels suppress metabolism first, then body temperature falls.
45 40 body temperature (oC) 35 30 25 20 15 10 5 0 -5 08/01/98 10/01/98 12/01/98 02/01/99 04/01/99 06/01/99
arousal and re-entry at ambient temperature -5oC 40 1000 metablic rate (ml O 2 /gm/hr) 2.4 body temperature (oC) 35 body 2.2 T b 2.0 temperature 30 750 1.8 . metabolic 25 1.6 rate VO 2 activity 1.4 20 500 1.2 15 1.0 BMR 10 0.8 250 0.6 5 basal metabolism act 0.4 activity 0 0.2 0.0 -5 0 0 5 10 15 20 25 30 35 40 45 hours Karpovich S, Toien O, CL Buck and Barnes BM. 2009. Energetics of arousal episodes under arctic conditions in arctic ground squirrels. J Comp Physiol 179 691-700
arousal and re-entry at ambient temperature -5oC metablic rate (ml O2/gm/hr) 0.8 40 1000 body temperature (oC) 35 body temperature T b 30 0.6 750 25 . activity metabolic BMR 20 0.4 VO 2 rate 500 15 10 0.2 250 5 act activity 0 0.0 -5 0 0 5 10 15 20 hours
Stroke and heart attack are a problem of: (Blood) supply = (metabolic) demand.
Stroke and heart attack are a problem of: (metabolic) demand. ( Blood) supply ≠
Stroke and heart attack are a problem of: ( Blood) supply (metabolic) demand. = Create stasis, time for transport to advanced medical care.
arousal and re-entry at ambient temperature -5oC metablic rate (ml O2/gm/hr) 0.8 40 1000 body temperature (oC) 35 body temperature T b 30 0.6 750 25 . activity metabolic BMR 20 0.4 VO 2 500 rate 15 10 0.2 250 5 act activity 0 0.0 -5 0 0 5 10 15 20 hours
Comparison of the mammalian hibernation phenotype in human-sized and small hibernators. American black bear Arctic ground squirrel
Photo by J. Hechtel
contrast of body temperatures during hibernation in small and large mammals 45 Hibernating black arctic ground squirrel 40 black bear bears are human- body temperature ( o C) sized, do not need 35 to eat, drink, 30 defecate or urinate for 7 months, do 25 not lose muscle or 20 bone mass, and can be wakened at 15 anytime. 10 5 0 -5 Tøien et al. 2011 Science Sep Oct Nov Dec Jan Feb Mar Apr May
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