Mechanism of suppression of physiological functions in hypothermia and means for their stimulation without body warming

Cold-suppressed thermoregulatory reactions and respiration in rats in deep hypothermia (rectal body temperature (25–22°C) were shown to be stimulated by injecting disodium ethylenediaminetetraacetic acid (EDTA) solution into the blood stream of cold rats at a dose of 16.5 mg/100 g (0.0045 mmol/100 g). EDTA binds Ca 2+ ions in the blood, forming complexes. Increases in cold shivering and pulmonary respiration (by 5 min after the start of administration) coincided with a reduction in the blood Ca 2+ concentration by 42–45% of normal. By 15 min after the start of the EDTA injection, the blood Ca 2+ concentration returned to the normal level present in cold rats before EDTA treatment. This was accompanied by suppression of cold shivering and pulmonary respiration. Repeated injection of EDTA into the blood stream produced a new drop in blood Ca 2+ and repeated stimulation of cold shivering and pulmonary respiration.