PACKARD, M.J.*; PACKARD, G.C.; Colo. State Univ.; Colo. State Univ.: Accumulation of Lactate and Glucose During Freezing of Hatchling Painted Turtles ( Chrysemys picta)

Hatchling painted turtles survived freezing at -2 &deg C for 4 days, but few animals recovered from freezing lasting 6 days, and no turtle survived being frozen for 8 days. Whole body glucose and lactate were low in animals that had not been subjected to tests of cold tolerance but increased precipitously in animals that were frozen for 2 days. Both metabolites continued to increase, but at a somewhat lower rate, in animals frozen for 4, 6, or 8 days. The increase in whole body lactate reflects a reliance by frozen hatchlings on anaerobiosis whereas the increase in glucose presumably results from mobilization of glycogen reserves to support anaerobic metabolism. Mortality of frozen hatchlings is correlated with the increase in whole body lactate, and the profound changes in physiology that force frozen hatchlings to rely exclusively on anaerobic metabolism may compromise a hatchling�s ability to cope with the ensuing lactic acidosis. Life in a frozen state obviates transport of glucose mobilized from reserves of glycogen in liver to other tissues. Thus, depletion of energy reserves in individual organs could contribute to the fact that frozen turtles are unable to survive conditions much less rigorous than those that are routinely survived by hatchlings in natural nests. Supported by NSF (IBN-0112283).