Suspended Animation In Mice Without Freezing

Predictions Market writes "Low doses of hydrogen sulfide, the toxic gas responsible for the unpleasant odor of rotten eggs, can safely and reversibly depress both metabolism and aspects of cardiovascular function in mice, producing a suspended-animation-like state that does not depend on a reduction in body temperature and include a substantial decrease in heart rate without a drop in blood pressure. The researchers measured factors such as heart rate, blood pressure, body temperature, respiration, and physical activity in normal mice exposed to low-dose (80 ppm) hydrogen sulfide for several hours. In all the mice, metabolic measurements such as consumption of oxygen and production of carbon dioxide dropped in as little as 10 minutes after they began inhaling hydrogen sulfide, remained low as long as the gas was administered, and returned to normal within 30 minutes of the resumption of a normal air supply. 'Producing a reversible hypometabolic state could allow organ function to be preserved when oxygen supply is limited, such as after a traumatic injury,' says the lead author of the study. 'We don't know yet if these results will be transferable to humans, so our next step will be to study the use of hydrogen sulfide in larger mammals.' The full report is available online."

Old News

[Smordnys s'regrepsA]

Can we get an update? There have already been tests involving pigs (lifted straight from the wikipedia [wikipedia.org] entry)

Induced hibernation

In 2005 it was shown that mice can be put into a state of suspended animation-like hypothermia by applying a low dosage of hydrogen sulfide (80 ppm H2S) in the air. The breathing rate of the animals sank from 120 to 10 breaths per minute and their temperature fell from 37 C to just 2 C above ambient temperature (in effect, they had become cold-blooded). The mice survived this procedure for 6 hours and afterwards showed no negative health consequences.[6] In 2006 it was shown that the blood pressure of mice treated in this fashion with hydrogen sulfide did not significantly decrease.[7]

Such a hibernation occurs naturally in many mammals and also in toads, but not in mice. (Mice can fall into a state called clinical torpor when food shortage occurs). If the H2S-induced hibernation can be made to work in humans, it could be useful in the emergency management of severely injured patients, and in the conservation of donated organs.

As mentioned above, hydrogen sulfide binds to cytochrome oxidase and thereby prevents oxygen from binding, which leads to the dramatic slowdown of metabolism. Animals and humans naturally produce some hydrogen sulfide in their body; researchers have proposed that the gas is used to regulate metabolic activity and body temperature, which would explain the above findings.[8]

However, a 2008 study failed to reproduce the effect in pigs, concluding that the effects seen in mice were not present in larger mammals. [9] [pccmjournal.com]

Re:I think that's not what they had in mind

[hitmark]

the problem is that the freezing creates ice, sharp ice...

still, sugar helps here i think...

Herbert West, Reanimator

[nten]

I read recently (on /. I think) that it was discovered the tissue damage was done when RISING o2 levels triggered apoptosis. Meaning there is actually a period as long as 2hrs where little or no tissue damage has occurred. If the o2 levels can be brought up in a way that keeps the trigger from thinking a massive o2 spike is about to mutate all the DNA we might realize the dream of Herbert West. I also read about this a while back and they didn't think it would scale to humans, but if it did, it might stack nicely to allow delaying reanimation even longer.

Re:Yeah but...

[Cyberax]

Actually, no. Your nose will be almost completely anaesthetized after several breaths.

That's actually a dangerous feature of hydrogen sulfide - it's quite poisonous and you can breath a fatal dose of it without even realizing that you're breathing a poison.

Re:I declare this year of the mouse!

[3waygeek]

Chopping up mice is old school -- this [milk.com] is how a real man prepares his mice.

Re:Yeah but...

[Teun]

The safe level to work in for 8 hours per day (MAC value), 5 days per week has recently been dropped from 10 ppm to 2 ppm.
80 ppm of H2S is going to be lethal after 8 -24 hrs of exposure, much earlier you will be suffering bleeding and other very unpleasant effects.
At 500 ppm you're dead in 30 to 60 minutes and at 800 ppm you will not survive 2 minutes.
The kicker is at 1000 ppm, you're immediately unconscious and will die within seconds.

You'll start smelling it at about 0.1 ppm but at otherwise not lethal concentrations it will desensitise your nose and you will eventually not realise it's still around or getting stronger.

As a side effect it has a much wider range of explosiveness than regular hydrocarbon gasses and because it's heavier than air it will concentrate at low places.

Iron and Apoptosis

[francisstp]

Yes, and iron is a big factor in this process apparently. When oxygen-filled blood finally reaches the damaged tissues, the liberated iron acts as a super free-radical and wreaks havoc.


I think the article you're referring to is http://www.newsweek.com/id/35045 [newsweek.com]