Physiology of hibernation inRana pipiens: metabolic rate, critical oxygen tension, and the effects of hypoxia on several plasma variables
✍ Scribed by Ultsch, Gordon R. ;Reese, Scott A. ;Stewart, E. Ray
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 153 KB
- Volume
- 301A
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Rates of O 2 consumption (
. VO 2 ) were determined for adult northern leopard frogs (Rana pipiens) submerged at 3 1C at water PO 2 s (P w O 2 ) ranging from 0-160 mmHg. The critical O 2 tension (P c ) was 36.4 mmHg. Hematocrit and blood levels of PO 2 , glucose, lactate, pH,
and osmolality were determined for frogs submerged for two days. Above a P w O 2 of 50 mmHg, blood PO 2 ranged from 1-7 mmHg, which was sufficient to allow the frogs to function entirely aerobically. Plasma [lactate] increased as P w O 2 fell below 50 mmHg, the increase preceding significant changes in any other variable, and apparently preceding a fall in . VO 2 . Most other variables showed little or no change from those of air-breathing control animals, even during anoxia. We present an analysis of the importance of a large decrease in P c in permitting frogs to successfully overwinter in icebound ponds and of the factors that contribute to that decrease.