X-Message-Number: 2618 From: (Sam Ralph) Newsgroups: sci.cryonics Subject: Re: Problem with Cryonics Date: 19 Feb 1994 21:06:28 GMT Message-ID: <2k5v0k$> References: <> <> Personally, I've never heard of freezing a dog or horse solid - and expect it to live. However, smaller animals like frogs and caterpillars can be frozen - often for weeks - and do just fine. These animals have two approaches, freeze solid or create some antifreeze. This isn't as silly as it sounds. Some caterpillars can have up to 40% of their blood volume present a small polyhydroxyalcohols. (like the stuff in your radiator). This amounts to when the mercury dips, they simply don't freeze. Frogs like rana sylvatica (sp?) do freeze, but not completely solid. Up to 65% of total body water is sequestered as ice. Earlier articles were correct in saying that ice doesn't form inside cells (it would wreak havoc on intracellular organisation). But rather, ice crystals must form outside and grow slowly so they don't damage cell membranes. The limit of 65% is imposed because rising osmotic pressure can crush membranes if the crystals don't do any damage. These frogs use glucose in ridiculously high concentrations to stave off freezing 100% of body water. This works for frogs, as for man well, it isn't quite that simple. There's also the question of reperfusion injury, but that's a whole other story. -- //Sam Ralph <> //Biochemistry Dept. //Memorial U of Newfoundland Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=2618