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Biological Miracle – Wood Frog

(www.nps.gov)
501 points thunderbong | 9 comments | 15 Nov 24 18:16 UTC | HN request time: 0.396s | source | bottom
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abound ◴[16 Nov 24 04:12 UTC] No.42154107[source]▶
> Nobody yet understands what starts the wood frog’s heart after being frozen and inert for the entire northern winter.

To me, that's the most fascinating part of the (already quite fascinating) story. Frog is frozen solid, there is no (to our knowledge) heartbeat or brain activity. It thaws and something happens that gets it going again.

I have trouble imagining what that mechanism could even look like. Tiny portion of brain responsible for keeping track of frozen-ness? Some chemical signaling from within the body cavity?

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1. PittleyDunkin ◴[16 Nov 24 04:53 UTC] No.42154392[source]▶
The frog is not frozen solid.
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2. PhasmaFelis ◴[16 Nov 24 04:57 UTC] No.42154406[source]▶
Interestingly, you can freeze a rat solid in liquid nitrogen--completely solid right through--and then thaw them out in a microwave and they actually survive. Well, many of them survive. For a while. Okay, it's not good for the rats but it's still crazy that it works.
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3. plastic3169 ◴[16 Nov 24 07:20 UTC] No.42155016[source]▶
Where can I read more about this? If this was a fact I think people would be way more excited about cryonics. Casually browsing wikipedia suggests that we are not there yet with the ability to thawn large animals or even organs.
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4. terribleperson ◴[16 Nov 24 07:47 UTC] No.42155115{3}[source]▶
I can't source this because I read it years ago, but I believe that there is some science that says that a major factor (not the only major factor, but a major factor) is body mass and volume. Essentially, the speed at which the core organs go from operating temperature to frozen is crucial, and it's also important for them to be deprived of oxygen when that happens. Humans are just... too big.
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5. blue_pants ◴[16 Nov 24 08:25 UTC] No.42155246{3}[source]▶
From https://en.wikipedia.org/wiki/James_Lovelock

"In the mid-1950s, Lovelock experimented with the cryopreservation of rodents, determining that hamsters could be frozen and revived successfully.[14] Hamsters were frozen with 60% of the water in the brain crystallised into ice with no adverse effects recorded. Other organs were shown to be susceptible to damage.[15]"

And there's a Tom Scott's interview with James Lovelock:

https://www.youtube.com/watch?v=2tdiKTSdE9Y

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6. mock-possum ◴[16 Nov 24 10:22 UTC] No.42155657{4}[source]▶
Wouldn’t it be crazy if only worked on hamsters
7. tim333 ◴[16 Nov 24 11:30 UTC] No.42155875{3}[source]▶
I was checking youtube to see if I could see that happen but failed - they were all about thawing rats to feed to snakes. There was however a goldfish dropped in liquid nitrogen briefly and recovering https://www.youtube.com/watch?v=wwolYFGM9pU
8. sriacha ◴[16 Nov 24 16:01 UTC] No.42157023{4}[source]▶
There are ways to adjust cooling rates... for example route the blood externally and chill it like they do in some kinds of surgery.
9. PhasmaFelis ◴[17 Nov 24 09:00 UTC] No.42162931{3}[source]▶
These experiments are exactly why people were excited about cryonics, until they realized that it doesn't work on anything much larger than a rat.

You have to thaw them right down to the core very quickly; you need to get the heart pumping or the thawed extremities will die with no bloodflow. There's no way to heat a human's core that fast without causing unsurvivable burns to their outside. (Even the rats wound up with nasty, sometimes fatal burns.)