From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Wed Nov 01 2000 - 09:27:15 MST
Title
Freeze duration influences
postfreeze survival in the frog Rana sylvatica.
Source
Journal of Experimental Zoology. 280(2):197-201, 1998 Feb 1.
Abstract
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.
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