Measurement of physiological parameters
Core body temperature was measured by rectal sensor RET-2 in rats (Physitemp, USA, ± 0.1°C). Measurement of metabolic parameters (oxygen consumption, carbon dioxide release, respiratory coefficient and energy release) was carried out using mm-100 metabolic monitoring system (CWE Inc., USA). Animals were housed in the chamber of 7.5 L. The rate of air flow was 1500 ml/min. The monitoring was carried out at room temperature in the specified time intervals including 3 min for the measurement.
We also used literature data on oxygen consumption by hibernating animals . In the calculations we assumed that in animals 1 ml of inhaled oxygen yields 20.1 Watt .