Abstract
Ten healthy male subjects (19-22 years old) were immersed to the neck in cold-spring water (13°C) for 15 min, twice a day, for consecutive 12 days. The urinary excretion of adrenaline increased transiently on the first day of the experiment. The urinary excretion of noradrenaline doubled on the first day of the experiment compared to the value before the cold exposure, and this increase was sustained throughout the study period. Serum cortisol level significantly rose at 15 min after the first immersion. However, this cortisol response to cold-water exposure was not seen at 11th and 23rd immersions. There were no significant changes in serum levels of thyroxine (T4), 3, 5, 3'-triiodothyronine (T3) and 3, 3', 5'-triiodothyronine (r-T3) by the acute cold-water exposure. The basal level of T3 rose significantly on the 12th day, whereas the basal level of T4 was unchanged throughout the study period. These results suggested that the intermittent severe cold-water stimuli evoke the similar hormonal responses to what have been reported in continuous exposure to cold air.
