A Comparison of Blood Buffering Capacity in Hibernators (Mesocricetu s auratus) and Non-hibernators (Mus musculus) Acclimated to a Cold and Short Photoperiod

Differences in blood buffering capacity and in blood glucose level homeostasis were examined in hibernators (golden hamsters) and non-hibernators (house mice) acclimated to a cold environment and short photoperiod. First, the pH and glucose levels were investigated in experimental animals maintained at a temperature of 22°C and a 12:12 light-dark cycle (control group) and then after a two-week period of adaptation to low ambient temperature and short photoperiod (temperature of 10°C and a 8:16 light-dark cycle) and additionally after 10 μl of 10% lactic acid was added to 450 μl of freshly collected blood samples. The pH of blood in cold acclimated animals decreased in comparison with control ones. In non-hibernators blood pH was significantly lower than in hibernators. The addition of lactic acid to blood samples results in a sharper drop of blood pH in non-hibernators than in hibernators. In control animals glucose levels didn't differ significantly between non-hibernators and hibernators, whereas after the cold acclimation period glucose levels in non-hibernators and hibernators stabilized at virtually the same but lower level. The results of blood glucose level measurements clearly indicated that this level – 130 mg/dl is the regulated level of glucose in the blood of both groups of animals. An improved buffering capacity of the blood revealed in hibernators could be considered as an adaptation to alleviate potentially negative effects of both respiratory acidosis and metabolic acidosis which accompany entrance into hibernation and arousal from hibernation. In conclusion the differences in buffering ability of blood to the resistance of changes of pH due to the addition of acid, revealed for non-hibernators and hibernators, indicate better adaptation of hibernators subjected to cold to their life in this environment.