Seasonal changes in blood rheology in little ground squirrels.

The annual cycle of small ground squirrels (Spermophilus pygmaeus) consists of 2 periods: wakefulness (spring-autumn) and hibernation (winter). During the active period, ground squirrels breed (spring), accumulate fat reserves (summer) and prepare for hibernation (autumn). We suppose that the rheological properties of blood and the deformability of erythrocytes can change in different seasons of the animal's wakefulness period to adequately provide tissues with oxygen.