Scientists have tried to unravel how some people who seemingly freeze to death, with no heart rate or respiration for extended periods, can be brought back to life with no long-term negative health consequences.
New findings from the lab of cell biologist Mark B. Roth, Fred Hutchinson Cancer Research Centre (FHCRC), may help explain the mechanics behind this widely documented phenomenon.
Roth and colleagues show that two widely divergent model organisms, yeast and nematodes, can survive hypothermia, or potentially lethal cold, if they are first put into a state of suspended animation by means of anoxia or extreme oxygen deprivation.
They found that under normal conditions, yeast and nematode embryos cannot survive extreme cold.
After 24 hours of exposure to temperatures just above freezing, 99 per cent of the creatures die. Conversely, if the organisms are first deprived of oxygen and thus enter a state of anoxia — induced suspended animation, 66 per cent of the yeast and 97 per cent of the nematode embryos will survive the cold. Once normal growth conditions are resumed — upon rewarming and reintroduction of oxygen — the organisms will reanimate and go on to live a normal lifespan.
A better understanding of the potentially beneficial, symbiotic relationship between low oxygen and low temperatures may one day lead to the development of improved techniques for extending the shelf life of human organs for transplantation, Roth said.
“We have found that extension of survival limits in the cold is possible if oxygen consumption is first diminished,” he said.