[Resuscitation of vital activity in intensively cooled animals by physiological methods without rewarming]

White rat males (Wistar) were cooled in the water (9-10 °C) to the stop breathing (at rectal temperature 14.7 ± 0.5°, brain 16.0 ± 0.3 °C). After the removal of water animals were injected 0.5% solution disodium salt ethylenediaminetetraacetic acid (Na2EDTA) intravenously, which reduced the concentration of Ca2+ in the blood. Breathing rats were resumed after 4-8 min after administration Na2EDTA. Then one group of rats was cooled to the temperature of the body 12.2 ± 0.7 (brain 14.9 ± 0.3 °C). At such a low temperatures the breath of rats was long-term (2-3 hours) supported at the level of 12 ± 3 cycle/min. The second group of rats was not additionally cooled after the resumption of breathing. The same dose of Na2EDTA caused the rise of the respiratory rate to a higher level--29 ± 4 cycles/min at a temperature in the rectum and the brain 15-16°. Apparently, the process of accumulation of Ca2+ in the cytoplasm of the respiratory center's cells was slowed after the Na2EDTA injection to hypothermal rats in the bloodstream. It is assumed that the Na2EDTA injection under the hypothermia conditions was activated the cell's protection mechanisms from cold damage. The obtained results and the literature data allowed to conclude that nonhibernators are able to maintain basic life functions under significant reduction in the body temperature.