Abstract

Freeze-tolerant frogs experience marked changes in their cellular chemistry as a result of internal freezing, forcing them to incur metabolic costs that are likely remedied upon thawing. This study measured levels of O₂ consumption in Rana sylvatica after freezing for one and seven days at −1.5 C and thawing at 5 C. Oxygen consumption was measured 4, 8, and 28 h after the onset of thawing. Following a one-day freeze, frogs had a 30% lower O₂ consumption value after 4 h into the recovery than their prefreeze rate. After the seven-day freeze, the O₂ consumption of frogs was nearly as low (−25%) at 4 h, but the reading at 8 h was more than 40% above the control level. Frogs had O₂ consumptions equivalent to the control at 28 h following both treatments. Low rates of O₂ consumption early in postfreeze recovery corresponds to depressed systemic functions in frogs, and the level of O₂ consumption at 8 h following the seven-day freeze was possibly linked to disturbance of the cellular environment.