Ten-day cold exposures develop adaptation-compensatory mechanisms of regulation of heat exchange and breathing.
The purpose of the study was to determine types of general cold adaptation and to reveal adaptation-compensatory regulation mechanisms of heat exchange and breathing. 24 healthy subjects were tested. Thermoregulation and gas exchange was measured before, during and after a 10-day cold exposure (13 degrees C, 2 h). Before and after cold exposures the ventilatory CO2 and O2 sensitivity was measured by the rebreathing method. The gas-analyser Eos Sprint ("Erich Jaeger", Germany) was used. The whole group exhibited the hypothermic isoinsulative adaptation type: during cold exposure Tre decreased (P < 0.01), Tsk did not change, the delay for the onset of shivering increased (P < 0.001), Tre of the onset of shivering decreased (P < 0.01). According to Tre measured at 120 min of the 10th day the group was divided in two. In the first group the adaptive response was based on thermoregulation changes only. In the second group adaptive response was based on both thermoregulation changes and breathing regulation changes: ventilatory CO2 and O2 sensitivity increased (P < 0.01), the oxyhaemoglobin dissociation curve moved to the right (P < 0.01). Thus we can propose that subjects of the first group will be more successful in cold adaptation, whereas the second group will be unsuccessful in cold adaptation and at risk for respiratory diseases.
Kovtoun
L T
LT
Institute of Physiology, Siberian Branch of Russian Academy of Medical Sciences. L.T.Kovtoun@iph.ma.nsk.ru
Krivoschekov
S G
SG
D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D001833:Body Temperature Regulation / Q000502:physiology*; D003080:Cold Temperature; D006358:Hot Temperature; D006801:Humans; D008297:Male; D012119:Respiration; D012800:Siberia