The Physiology of Hibernation in Canadian Leopard Frogs (Rana pipiens) and Bullfrogs (Rana catesbeiana)

• Published in: Physiological and biochemical zoology 2004-01, Vol.77 (1), p.65-73
• Main Authors: Stewart, E. Ray, Reese, Scott A., Ultsch, Gordon R.
• Format: Article
• Language: English
• Subjects: Anaerobiosis; Analysis of Variance; Animals; Anoxia; Blood Chemical Analysis; Carbon Dioxide - blood; Frogs; Hematocrit; Hibernation; Hibernation - physiology; Hydrogen-Ion Concentration; Hypoxia; Hypoxia - physiopathology; Lactates; Low temperature; Manitoba; Overwintering; Oxygen - blood; Quebec; Rana catesbeiana; Rana catesbeiana - physiology; Rana pipiens; Rana pipiens - physiology; Temperature; Time Factors; Turtles
• ISSN: 1522-2152; 1537-5293
• DOI: 10.1086/378921

Canadian northern leopard frogs (Rana pipiens)and bullfrogs (Rana catesbeiana) were acclimated to 3°C and submerged in anoxic (0–5 mmHg) and normoxic (Po 2∼158 mmHg) water. Periodic measurements of blood Po 2, Pco 2, and pH were made on samples taken anaerobically from subsets of each species. Blood plasma was analyzed for [Na+], [K+], [Cl−], [lactate], [glucose], total calcium, total magnesium, and osmolality. Blood hematocrit was determined, and plasma bicarbonate concentration was calculated. Both species died within 4 d of anoxic submergence. Anoxia intolerance would rule out hibernation in mud, which is anoxic. Both species survived long periods of normoxic submergence (R. pipiens, 125 d;R. catesbeiana, 150 d) with minimal changes in acid‐base and ionic status. We conclude that ranid frogs require a hibernaculum where the water has a high enough Po 2to drive cutaneous diffusion, allowing the frogs to extract enough O2to maintain aerobic metabolism, but that an ability to tolerate anoxia for several days may still be ecologically meaningful.