X-Message-Number: 22747
Date: Wed, 29 Oct 2003 20:31:01 -0800 (PST)
From: Doug Skrecky <>
Subject: freeze tolerant frogs survive 49 days of frozen storage

J Exp Zool. 1998 Feb 1;280(2):197-201.
Freeze duration influences postfreeze survival in the frog Rana sylvatica.

	Survival, cryoprotection, and the time course for recovery of
vital functions were studied in autumn-collected juvenile wood frogs
(Rana sylvatica) following freezing at -1.5 degrees C for various
periods. Frogs readily tolerated freezing for 3 or 9 d, but only 50%
survived a 28-d freezing trial. Generally, the postfreeze return of vital
functions (vascular circulation, pulmonary breathing, righting reflex,
jumping reflex) occurred later in frogs frozen for longer periods.
Augmenting endogenous levels of the cryoprotectant glucose (via
injections) prior to freezing substantially increased freeze endurance, as
these frogs had excellent survival after remaining frozen for as long as
49 d. The improved freeze endurance of glucose-loaded frogs apparently
was not associated with a reduction in ice content but rather may reflect
the greater availability of energy substrate needed to support metabolism
of frozen ischemic tissues.

Comment by poster:
	Using the freeze tolerant frog as a subject for cryonics research
might help to make a breakthrough in fully reversible liquid nitrogen storage.

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