From: Geoff Smith (geoffs@unixg.ubc.ca)
Date: Sun Sep 14 1997 - 14:44:56 MDT
On 14 Sep 1997, Anders Sandberg wrote:
> Geoff Smith <geoffs@unixg.ubc.ca> writes:
>
> > On 12 Sep 1997, Anders Sandberg wrote:
> >
> > > Actually, this is what occurs when the body is frozen. Ice forms
> > > *between* the cells, not inside them, and they are largely dehydrated.
> > > Causes damage too, unfortunately.
> >
> > Excuse my obvious ignorance of this subject. How exactly does this
> > happen? What causes the transport of water out of the cytoplasm and
> > through the cell membrane when the cell is being frozen? I assume if
> > freezing is done quickly, the resulting dehydration of the cell is a rapid
> > process. Wouldn't the sudden increase in volume of intersitial fluid
> > damage the cells before the water even froze?
>
> Actually, there is no need to excuse one's ignorance unless one
> should have paid attention. A willingness to learn and an awareness
> of what one doesn't know is only healthy!
>
> Ice is pure water (other chemicals don't fit into the crystal lattice),
> so when interstitial fluid freezes it will become more concentrated
> since the other chemicals don't get frozen. This will lead to an
> osmotic imbalance between the cells and the surroundings, which will
> cause water to leave the cells. Since concentrated solutions also
> freeze at lower temperatures than dilute solutions the cells will
> not freeze until they reach the vitrification temperature, where
> the water molecules simply form a glass (not a crystal); if we
> could somehow vitrify tissues, then cryonics would have much better
> chances.
Could this be achieved by saturating the tissue with ions, say by
administering large doses of a salt like KCl? (KCl is a bad example,
obviously, but maybe a more benign salt?)
How about drinking antifreeze? ( and ethanol, of course, to cancel the
toxic effects of alcohol dehydrogenase on antifreeze)
What is the vitrification temperature?
thx,
geoff.
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