Hibernating bears may help sick humans

The American black bear stays warm when it hibernates. If sick humans could do that, they could heal better, scientists say.
The American black bear stays warm when it hibernates. If sick humans could do that, they could heal better, scientists say. (Institute Of Arctic Biology, University Of Alaska Fairbanks Via Associated Press)
Monday, March 7, 2011

Hibernating bears set their energy demands on low; but unlike most other animals that take long winter naps, they don't chill out very much, researchers have reported.

Figuring out how bears cut energy use but still keep their body temperature relatively warm could one day help doctors treat people who have suffered heart attacks and strokes.

The body temperature of small hibernating mammals can drop to near freezing. But that is not the case for black bears, according to new research.

The study's senior author, Brian M. Barnes of the University of Alaska, and his colleagues studied five black bears that Alaska wildlife officials had removed from areas near people.

The bears hibernated wooden nest boxes fitted with cameras and sound recorders as well as instruments to measure oxygen use. All of the bears had implanted transmitters to measure their temperature, heart rate and muscle activity.

The scientists found that rather than having their temperature drop to near freezing, the bears went through cycles of several days when their temperature fell to 86 degrees. Then they began shivering, and the readings climbed back to about 97 degrees, nearly normal.

However, even though they remained relatively warm, the bears' metabolism slowed significantly. (Metabolism is the set of functions a body needs to do to stay alive, including using oxygen and burning calories.) Hibernating bears used 75 percent less oxygen than in summer; their heart rate fell from 55 beats per minute to 14.

While it would take a lot more research, doctors might one day be able to place very seriously ill people in a state like hibernation until they got better.

In another surprise, the researchers discovered that bears, like groggy people in the morning, are slow to recover from hibernation. Their metabolism didn't return to normal levels for several weeks.

- Associated Press


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