Saturday, April 22, 2017

Wisdom Of The Week

Naked mole rats are tough creatures — they can withstand cancer, pain, and even survive 18 minute stretches without any oxygen. And now, scientists have a better idea of how the super rodents can survive that long without suffocating. The findings, published today in the journal Science, could one day help researchers figure out how to keep humans healthy when oxygen gets cut off by strokes or heart failure.

Naked mole rats are wrinkly, hairless, poop-eating, delightful creatures that live in large colonies of up to 280 animals. They spend their lives crawling through tunnel networks beneath the deserts of Africa — where the air can get a little stuffy, and very low on oxygen. On the surface, carbon dioxide makes up less than one percent of the gases we breathe. But in these tunnels, carbon dioxide can account for 7 to 10 percent of the warm, close air.

For most creatures, these conditions would be unlivable. We need oxygen to survive, because oxygen is key for generating the energy our bodies rely on to function. Cut off the oxygen, and we humans start hyperventilating, panicking, and having acid build up in our tissues. In the long run, we can experience serious brain damage, or even death.

But even if oxygen is low, the naked mole rats are … fine. And scientists wanted to understand how that’s possible. So, after getting approval from an ethics committee, the researchers led by put naked mole rats in atmospheric chambers — basically, sealed tubes — and started dialing back the oxygen levels. They saw that, even when oxygen levels dropped to just five percent of the gases in the tube (atmospheric oxygen levels are typically closer to 21 percent) the rats were fine for five hours. Mice, by contrast, suffocated and died after just 15 minutes.

When the oxygen was completely removed and replaced with nitrogen, the mice died after 45 seconds. The naked mole rats passed out. But even after 18 minutes of no oxygen, they recovered when they were put back in normal air. (30 minutes of no oxygen was another story — they died.)

So how do the naked mole rats do it? Apparently, the rodents go into a kind of suspended animation, which reduces their little bodies’ energy demands. What’s more, the researchers discovered that fructose levels rose in the naked mole rats’ tissues compared to in mice. They also found pumps that funnel fructose into cells in the heart and brain — whereas in mice, these pumps are mainly in the kidneys. That suggests the naked mole rats switched to a kind of oxygen-free metabolism that relied on fructose, instead of glucose.


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