The population composition of erythrocytes as an indicator of adaptation of a hibernating mammal to unfavourable environmental factors

This study aimed to investigate the population composition of erythrocytes in ground squirrels during deep hibernation and at various stages of rewarming upon induced arousal.

The study was conducted on little ground squirrels (Spermophilus pygmaeus Pall.). Experiments were performed on awake animals (control), animals in the middle of a deep hibernation bout, and in various stages of induced arousal (with body temperatures of 15 °C, 25 °C, and 37 °C). The population composition of erythrocytes was assessed using the acid erythrogram method.

During hibernation, an increase was observed in the number of erythrocytes undergoing spherocytic transformation, accompanied by a rise in the proportion of highly‐resistant and ultra‐highly resistant cells. Arousal and an increase in body temperature to 15 °C led to a decrease in the proportion of erythrocytes with low and medium resistance compared to the arousal state. Rewarming of ground squirrels to 25 °C was characterised by a higher content of spherulated and low‐resistance erythrocytes compared to all other states. Conversely, the population of highly resistant erythrocytes showed a significant decrease relative to the previous stages of the study. The level of ultra‐highly resistant cells remained relatively high compared to the winter control. Achieving a body temperature of 37 °C did not result in complete normalisation of the erythrocyte population composition.

During the hibernation–arousal cycle, the population composition of erythrocytes undergoes significant changes. These may be attributed both to alterations within the erythron system and to structural modifications of erythrocyte membranes, which change their sensitivity to hemolytic agents.

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