IUPS 2013: A fascinating diversion into bears...

I was fortunate enough to catch the last bit of a session led by Henry Harlow of the University of Wyoming, describing his work on hibernating bears. Amazingly, during their winter slumber, bears loose only 20% of their muscle mass, whereas equivalent confinement in humans (e.g. Remaining on a hospital bed for 150 days) results in 70% loss of muscle. How do they do it? During the 5 months of their hibernation, bears do not urinate at all: by using radioactive isotopes, Harlow and his colleagues showed that the urea is broken down by gut microorganisms to release ammonia, which is recycled into building muscles. This session almost made me regret moving away from zoology and animal physiology although the idea of performing surgical implants on hibernating bears doesn't appear entirely risk free to me. Although some may argue this research is purely 'academic interest' understanding the physiology of fasting in bears is highly relevant in a world where we are limiting the hunting season for polar bears through our impact on global climate.  A sobering thought for the bears' futures - can their remarkable physiologist help them pull through?