WASHINGTON, April 20 (Xinhua) -- Naked mole-rats are able to survive for at least five hours at oxygen levels low enough to kill a human within minutes, scientists said Thursday.
That's because the East African animals under such conditions will switch to a metabolic mechanism that makes use of fructose just as plants do, according to the study in the U.S. journal Science.
The findings could help scientists develop treatments for patients suffering crises of oxygen deprivation, as in heart attacks and strokes.
"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.
Thomas Park led a team that also included researchers from the Max Delbruck Institute in Berlin and the University of Pretoria in South Africa.
In humans, laboratory mice, and all other known mammals, when brain cells are starved of oxygen they run out of energy and begin to die.
But naked mole-rats have a backup: their brain cells start burning fructose, which produces energy anaerobically through a metabolic pathway that is only used by plants, the researchers said.
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.
The fructose, the scientists found, was transported into brain cells by molecular fructose pumps that in all other mammals are found only on cells of the intestine.
"The naked mole-rat has simply rearranged some basic building-blocks of metabolism to make it super-tolerant to low oxygen conditions," said Park, who has studied the strange species for 18 years.
Without oxygen, the mice died within 20 seconds, but naked mole-rats could withstand up to 18 minutes without any lasting damage, they found.
Under such conditions, these animals will go into a state of suspended animation, reducing their movement and dramatically slowing their pulse and breathing rate to conserve energy.
But they will start stirring again as if nothing ever happened, within seconds upon exposure to air.
The naked mole-rat is the only known mammal to use suspended animation to survive oxygen deprivation.
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 scientists described the naked mole-rats' unusual metabolism as an adaptation for living in their oxygen-poor burrows.
Unlike other subterranean mammals, naked mole-rats live in hyper-crowded conditions, packed in with hundreds of colony mates, they said. With so many animals living together in unventilated tunnels, oxygen supplies are quickly depleted.
