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Titolo:
HYPOMETABOLIC HOMEOSTASIS IN OVERWINTERING AQUATIC AMPHIBIANS
Autore:
BOUTILIER RG; DONOHOE PH; TATTERSALL GJ; WEST TG;
Indirizzi:
UNIV CAMBRIDGE,DEPT ZOOL,DOWNING ST CAMBRIDGE CB2 3EJ ENGLAND
Titolo Testata:
Journal of Experimental Biology
fascicolo: 2, volume: 200, anno: 1997,
pagine: 387 - 400
SICI:
0022-0949(1997)200:2<387:HHIOAA>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
CHRYSEMYS-PICTA-BELLII; BLOOD ACID-BASE; ENERGY-METABOLISM; FREEZE TOLERANCE; EXTRACELLULAR PH; RANA-CATESBEIANA; GAS-EXCHANGE; CRUCIAN CARP; ANOXIC SUBMERGENCE; CEREBRAL-CORTEX;
Keywords:
METABOLIC SUPPRESSION; AQUATIC AMPHIBIAN; OVERWINTERING; ACID-BASE BALANCE; ION CHANNEL SUPPRESSION; COLD TORPOR; CUTANEOUS GAS EXCHANGE; OSMOTIC HOMEOSTASIS;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
121
Recensione:
Indirizzi per estratti:
Citazione:
R.G. Boutilier et al., "HYPOMETABOLIC HOMEOSTASIS IN OVERWINTERING AQUATIC AMPHIBIANS", Journal of Experimental Biology, 200(2), 1997, pp. 387-400

Abstract

Many amphibians encounter conditions each winter when their body temperature is so low that normal activities are suspended and the animalsenter into a state of torpor. In ice-covered ponds or lakes, oxygen levels may also become limiting, thereby forcing animals to endure prolonged periods of severe hypoxia or anoxia. Certain frogs (e.g. Rana temporaria) can dramatically suppress their metabolism in anoxia but arenot as tolerant as other facultative vertebrate anaerobes (e.g. turtle, goldfish) of prolonged periods of complete O-2 lack, Many overwintering amphibians do, however, tolerate prolonged bouts of severe hypoxia, relying exclusively on cutaneous gas exchange, Rana temporaria overwintering for 2 months in hypoxic water (P-O2 approximately 25 mmHg) at 3 degrees C progressively reduce their blood P-CO2 to levels characteristic of water-breathing fish, The result is that blood pH rises andpresumably facilitates transcutaneous O-2 transfer by increasing Hb O-2-affinity. Even after months of severe hypoxia, there is no substantial build-up of lactate as the animals continue to rely on cutaneous gas exchange to satisfy the requirements of a suppressed aerobic metabolism, Our recent experiments have shown that the skeletal muscle of frogs oxyconforms in vitro to the amount of O-2 available, The cellular basis for the oxyconformation of skeletal muscle is unknown, but the hypothesis driving our continuing experiments theorises that metabolic suppression at a cellular level is synonymous with suppressed ion leakacross cellular membranes.

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Documento generato il 11/07/20 alle ore 11:19:24