高濃度炭酸水がヒトの心自律神経活動に与える影響

抄録

CO₂ water immersion at 1000 ppm affects thermoregulation through the increased cutaneous blood flow on the immersed skin area. However, the effect of CO₂ water immersion on cardiovascular function remains to be clarified in humans. To examine whether CO₂ bathing affects cardiac autonomic function, we analyzed heart rate variability and measured the cardiac output by Echo (Apio XV, Toshiba, Japan) during CO₂ and fresh water immersion. Tympanic temperature (thermistor thermometry), cutaneous blood flow (laser-Doppler flowmetry) and electrocardiogram (ECG) were monitored continuously. The subjective thermal and comfort sensations were asked every 10-min during experiments. After a rest for 10 min, the subject immersed up to the breast level to CO₂-rich water at 1000ppm or fresh water at thermoneutral water. The results were shown as follows: 1) HF was significantly higher in CO₂ water immersion than in fresh water immersion. 2) LF/HF ratio was significantly lower in CO₂ water immersion than in fresh water immersion. 3) Heart rate was not significantly different between CO₂ water and fresh water immersion. 4) Tympanic temperature was significantly lower during CO₂ water immersion than during fresh water immersion. 5) Cutaneous blood flow in immersed forearm was significantly higher during CO₂ water immersion than during fresh water immersion. [J Physiol Sci. 2006;56 Suppl:S96]