Oxidative damage and antioxidants in rana sylvatica, the freeze
tolerant wood frog.
Joanisse, Denis R., and Kenneth B. Storey.
Institute of Biochemistry and Department of Biology, Carleton
University, Ottawa, Ontario, Canada K1S 5B6
APStracts 3:0055R, 1996.
Freeze tolerant wood frogs Rana sylvatica must endure prolonged
ischemia upon freezing. Reperfusion upon thawing brings with it the
potential for oxidative damage due to reactive oxygen species
formation, a well known consequence of mammalian ischemia
-reperfusion. To determine whether oxidative damage occurs during
thawing and how frogs deal with this we examined oxidative damage,
antioxidant, and pro-oxidant systems in tissues of Rana sylvatica and
a non-freezing relative, Rana pipiens. Glutathione status indicated
little oxidative stress in tissues during freezing or thawing, an
increase of the glutathione pool in the oxidized form observed during
freezing only in Rana sylvatica kidney (by 85%) and brain (by 33%).
Oxidative damage to tissue lipids, measured as the levels of
thiobarbituric acid reactive substances and/or by an Fe(III)-xylenol
orange assay, did not increase above control values over a freeze
-thaw time course. Correlative data showing increased activities of
some antioxidant enzymes during freezing, notably glutathione
peroxidase (increasing 1.2- to 2.5-fold), as well as constitutively
higher activities of antioxidant enzymes and higher levels of
glutathione in the freeze tolerant species when compared to Rana
pipiens, suggest that antioxidant defenses play a key role in
amphibian freeze tolerance.
Received 30 August 1995; accepted in final form 7 February 1996.
APS Manuscript Number R542-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96