title: The physiology of hibernation in Canadian leopard frogs (Rana pipiens) and bullfrogs (Rana catesbeiana).
abstract: Canadian northern leopard frogs (Rana pipiens) and bullfrogs (Rana catesbeiana) were acclimated to 3 degrees C and submerged in anoxic (0-5 mmHg) and normoxic (Po(2) approximately 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(2) to drive cutaneous diffusion, allowing the frogs to extract enough O(2) to maintain aerobic metabolism, but that an ability to tolerate anoxia for several days may still be ecologically meaningful.
authors.affiliation: Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487-0344, USA.
authors.forename: E Ray
authors.initials: ER
authors.lastname: Stewart
authors.forename: Scott A
authors.initials: SA
authors.lastname: Reese
authors.forename: Gordon R
authors.initials: GR
authors.lastname: Ultsch
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001774:Blood Chemical Analysis; D002245:Carbon Dioxide / Q000097:blood; D006605:Hibernation / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000503:physiopathology*; D008350:Manitoba; D010100:Oxygen / Q000097:blood; D011792:Quebec; D011892:Rana catesbeiana / Q000502:physiology*; D011894:Rana pipiens / Q000502:physiology*; D013696:Temperature; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen