In this study, we investigated the effect of bathing with cut crude drugs on thermal preservability, water holding capacity, and smoothness of the feel. After immersion with cut crude drugs of 5min at 41°C, the forearm skin core temperature was significantly higher than after plain water bathing. Water sorption-desorption tests on the skin in vivo with cut crude drug extract for the functional assessment of the stratum corneum revealed that the GARENIAE FRUCTUS extract, all of cut crude drugs extract, and FOENICULI FRUCTUS extract are significantly superior to plain water bathing in water holding capacity.
Furthermore, an evaluation using a skin model revealed that cut crude drugs have effects significantly superior to that of plain water bathing in increasing the smoothness of the feel. The above results clarified that bathing with cut crude drugs has a stronger effect on thermal preservability and that their extract increases water holding capacity and smoothness of the feel.

As a preparatory study for treating diabetic neuropathy by acupuncture, we investigated the effect of electroacupuncture on the sciatic blood flow in rats. Nerve blood flow was measured with a laser doppler flowmeter. Different treatments were applied to three groups of rats as follows:
1) those stimulated with low-frequency (1Hz, 5Hz) electroacupuncture,
2) those stimulated with high-frequency (20Hz, 100Hz) electroacupuncture and
3) those stimulated by pinching in the tails.
In the electroacupuncture groups, stimulation was applied to the plantae. While little change was observed in the rats stimulated with low-frequency electroacupuncture, temporary increases in both blood flow and blood pressure were observed in the rats stimulated with high-frequency electroacupuncture and in the rats subjected to pinch stimulation.
These reactions were all inhibited by the administration of phentolamine (α receptor blocker).
These results suggest that the increase in sciatic blood flow induced by high-frequency electroacupuncture and pinch simulation are dependent on the blood pressure.

We have been proceeding with studies on the effects of water immersion on autonomic nerve activity using the power spectral analysis of heart rate variability. The results obtained so far suggest that cardiac parasympathetic nerve activity is enhanced and sympathetic nerve activity is suppressed during immersion at temperatures between 25°C and 34°C and that parasympathetic nerve activity is suppressed and sympathetic nerve activity is enhanced during immersion at temperatures around 38°C. However, water immersion affects the respiration rate and tidal volume, and though the change in the respiration rate does not affect the real cardiac autonomic nerve activity, it affects the index of autonomic nerve activity as assessed by the power spectral analysis of heart rate variability. Therefore, this study examined the changes in cardiac autonomic nerve activity during water immersion with the tidal volume measured and its changes considered while controlling the respiration to a certain level. Eight healthy young males (ages: 19 to 28) sat calmly for 20 minutes before immersion and then soaked in water at the subaxillary level in sitting position for 15 minutes while controlling their respiration rate to 15cycles/min. Autonomic nerve activity was estimated by the power spectral analysis of the heart rate together with the Fast Fourier Transformation. Integral values of power were obtained in the high frequency (HF; 0.15 to 0.50Hz) and low frequency (LF; 0.04 to 0.15Hz) component areas. HF was used as the index of cardiac parasympathetic nerve activity, and the ratio of LF to HF (LF/HF), as the index of cardiac sympathetic nerve activity. During immersion at 34°C, HF increased significantly and the heart rate and LF/HF decreased slightly though not at a statistically significant level. During immersion at 27°C, HF increased significantly and the heart rate and LF/HF decreased significantly. During immersion at 38°C, the heart rate increased significantly while HF decreased and LF/HF varied slightly with no statistical significance. The tidal volume increased significantly during immersion at 27°C and 34°C, and it increased during immersion at 38°C though it was not statistically significant.
These results suggest that cardiac parasympathetic nerve activity is enhanced while sympathetic nerve activity is suppressed during immersion at 27°C, because the remarkable increase in HF that occurred during immersion cannot be accounted for by the increase in the tidal volume per breathing cycle alone. However, it is possible that the increase in the tidal volume enhanced the increase in HF. It was suggested, however, that autonomic nerve activities did not change significantly during water immersion at 38°C though there is possibility that the changes in HF were underestimated due to the increase in the tidal volume.

It is well known that gynecological complaints are ameliorated by hot spring bathing. We therefore investigated the changes in urinary mucin excretion before and after 14 days of daily hot spring bathing in order to clarify the relationship between hot spring bathing and complaint amelioration. Urine was collected from 28 female adults (64.3±7.0 years old) before and after the 14 days of hot spring bathing. Urinary mucins containing sialoglycopeptides and sulfated glycopeptides were separated from the urine using the ethanol and cetylpyridinium chloride precipitation methods, then indentified with two-dimensional electrophoresis on cellulose acetate membranes.
After the removal of glycosaminoglycan contamination by glycosaminoglycan-degrading enzymes, mucin amounts were determined by the phenol-sulfuric acid method. The results showed that the levels of both sialoglycopeptides and sulfated glycopeptides increased after 2 weeks of bathing. The level of urinary mucin, which is synthesized and excreted from the epithelial cells, increased as a result of hot-spring bathing. Therefore, it is highly likely that the amelioration of gynecological complaints of females is related to the chages in urinary mucin excretion brought about by hot spring bathing.

A 3-min bath in 47°C hot-spring water called ‘jikan-yu’ has been recommended for over 130 years at Kusatsu-spa. There is a traditional custom of pouring hot-spring water of the same temperature over the head before entering the bath to avert an afflux of blood to the brain. The medical significance of this custom was investigated in 8 healthy male volunteers (age 31±6 years and body mass index 22.4±1.6kg/m²). There were no significant differences in plasma levels of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), cortisol, and β-endorphin on a comparison of findings before and after the action of pouring 20 pails of 47°C hot-spring water over the parietal and occipital areas of the head. However, the direct effect of heat stress on the internal thermosensor in the anterior hypothalamus regulating heat loss and thermogenesis was not examined in this study. Thus, it is considered that the action does not provide a direct hyperthermal stimulus to the brain stem to release stress hormones but may dilate blood vessels of the head to prepare for the abrupt afflux into the cerebral circulation of blood heated by subsequent very hot hot-spring bathing.

In order to investigate the effects of the concentration of chemical components of sea water on thermoregulatory functions, rectal, skin and mean body temperatures were measured continuously before, during total body bathing as well as during recovery period on land.
Eight healthy young men were subjected in the experiment. Their physical characteristics were in average 19.8±1.0yrs in age, 169.2±5.0cm in height, 57.1±3.1kg in weight and 14.0±2.6% in body fat fraction, respectively. Each subject bathed in sea water or in tap water for 15 minutes in the long-sitting position at 38.5°C of water temperature during bathing and took recovery on land for 60 minutes. Water bathing was conducted in individual subject with the concentration of chemical components of sea water at 0, 1, 3.5 and 7%, respectively.
The rectal temperature increased during bathing and decreased gradually during recovery period on land. Statistically significant difference (p<.05) between 0 and 7% of the concentration of sea water was detected in the rectal temperature during bathing and recovery period. The mean skin temperature showed a continuous increase during bathing and showed a rapid decrease during 20 minutes in recovery, and a gradual decrease after then. Statistically significant difference (p<.05) between 0 and 7% of the concentration of sea water was detected in the mean skin temperatures during recovery period. The mean body temperature also showed a continuous increase during bathing and rapid decrease during the first 20 minutes in the recovery period, and decreased gradually thereafter. Statistically significant difference (p<.01) between 0 and 7% of the concentration of sea water was detected in the mean body temperature during bathing and recovery period.