Naked mole-rats were already impressive: they’re a cold-blooded mammal that outlives other rodents by decades, seldom get cancer, and are unfazed by many types of pain. Now researchers have added a new ability to the list with the discovery that naked mole rats can survive long periods with very little oxygen. Thomas Park and colleagues exposed naked mole-rats to low oxygen conditions, enough to kill a human within minutes, and found that they released large amounts of fructose into the bloodstream, enabling the naked mole-rat to survive for at least five hours. The discovery could have implications for humans during times of extreme oxygen deprivation, for example during a heart attack or stroke.
There were already several clues that the naked mole-rat could be extremely tolerant to oxygen deprivation. It has been known for some time that the hemoglobin in their blood is very sticky for oxygen, able to grab oxygen molecules out of atmospheres with very low oxygen levels. Also, they reduce their need for oxygen by not generating body heat—they are the only cold-blooded mammal. Keeping warm takes a huge amount of energy which normally requires a huge amount of oxygen. The naked mole-rats also have a much lower metabolism compared to other mammals. All of these traits suggest that naked mole-rat physiology is geared for being able to survive periods of low oxygen.