No oxygen? No problem for naked mole rats

Naked mole rats are highly social creatures that snuggle together for warmth.

It may have missed out on good looks, but the naked mole rat is once again amazing scientists with its fascinating super powers.

Although it was known that the little subterranean creatures never develop cancer, and live far longer than similar-sized mammals, researchers have now discovered they can also survive for 18 minutes without oxygen. What is even more astonishing is how they manage it.

They effectively become plants, altering their metabolism so that cells are powered by fructose rather than glucose, a process which requires no oxygen. The unique back-up system completely protects sensitive organs such as the heart and brain.

Scientists believe that it may be possible to trigger the same metabolism shift in humans who have suffered heart attacks or strokes, where most of the damage occurs because cells are starved of oxygen, and then die.

"Our work is the first evidence that a mammal switches to fructose as a fuel," said Professor Gary Lewin, of the Max Delbruck Centre of Molecular Medicine in Berlin.

"Patients who suffer an infarction or stroke experience irreparable damage after just a few minutes of oxygen deprivation. Theoretically, very few changes might be needed to adopt this unusual metabolism."

Researchers found that the bodies of naked mole rats are flooded with molecules and enzymes which allows fructose to be metabolised.

Humans need an atmosphere that has at least 10 per cent oxygen to survive, but naked mole rats have evolved to live in stuffy underground burrows in the African desert which can be 25km long, and have little air.

They are also highly social creatures that snuggle together at night for warmth, but can end up nearly suffocating if they are trapped in the middle of a "mole ball".

In the new study, the researchers exposed naked mole rats to low oxygen conditions in the laboratory and found that they released large amounts of fructose into the bloodstream, a metabolic process previously only seen in plants.

The experiment showed they can survive 18 minutes of complete oxygen deprivation by falling into a kind of suspended animation. When this happens their heart rate drops from 200 beats per minute to around 50.

But crucially, once they get a sniff of oxygen they start moving again as if nothing happened, and suffer no lasting damage.

"This is just the latest remarkable discovery about the naked mole rat - a cold-blooded mammal that lives decades longer than other rodents, rarely gets cancer, and doesn't feel many types of pain," said Thomas Park, professor of biological sciences at the University of Illinois at Chicago, who let the research. "The naked mole rat has simply rearranged some basic building-blocks of metabolism to make it super-tolerant to low oxygen conditions."

The scientists also showed that naked mole rats are protected from another deadly aspect of low oxygen - a buildup of fluid in the lungs called pulmonary edema that afflicts mountain climbers at high altitude.

The research was published in the journal Science.