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.

Using BASUKURIN, an inorganic salts, its power of relieving bathers of their subjective symptom was analysized by main component analysis.
Subjects were 30 patients per each of 6 groups of disease, i. e. neuralgia, rheumatism lumbago, stiff shoulder, contusion and distorsion, with only cases of more than 2 week-suffering for the latter of 2 diseases Bathing test was performed in 400L of elevator bath added with 34g of BASUKURIN compsed mainly of sodium bicarbonate and sodium sulphate and with 23g of placebo composed mainly of granuated sugar, respectively. Both bath drugs, supplied by Tsumuar Juntendo Inc., were jasmin-odored. In some caces, 50 L-partial bath was also used. According to the double blind method, those subjects were bathed successively in BASUKURIN-bath and pracebo-one for 3 consecutive days, and asked for their answers to the enquete about the difference which they possibly felt there between. The choice of which bath was arbitrary. Bathing was taken at 40°C for 10min. The enquete comprised 17 items to which subjectively expressed answers were corresponded, which answers being evaluated 7 stepwise.
(1) For the neuralgia group, effects were observed as “physiologically improved” and/or “getting warmed”. Improvement were made mainly in pain perception disorder and joint dysfunction.
(2) For the rheumatism group, effects were observed generally as “getting warmed”, and as “feeling familiar” and/or “feeling refreshed” for the case of skin hypersensitiveness.
(3) For the lumbago group, effects were observed also as “getting warmed” frequently, and as “feeling similar like hot spring” and/or “feeling familiar” for the relief of muscle hypertonus.
(4) For the stiff shoulder group, effects were observed not only as “getting warmed” generally, but also on the dysfunction of cervico-shoulder-arm and as “feeling familiar” for the relief of muscle hypertonus,
(5) For the contusion group, effects were observed as “feeling refreshed”, “feeling kept warmed”, “feeling familiar”, “feeling affined”, etc. accompanying with the local pain, malaise, cold sensation and so on.
(6) For the distorsion group, effects were observed characteristically as “feeling familiar” and “improved circulation” accompanying with circulatory insufficiency of the lower extremities.
As mentioned above, from the viewpoint by diseases, main symptoms will be improved directly, and improvements will be expressed as in the disease itself. On the other hand, from the overall viewpoint, score of improvements will be leveled, so that “getting warmed” and “feeling warmth” will be emphasized as common factors. Improvements, however, may be ascribable to the effects of both sodium bicarbonate and sodium sulphate as main ingredients of BASUKURIN.

The warming effect of natrium-hydrogen carbonate-sulfate springs was evaluated experimentally using rabbits with Na₂SO₄·NaHCO₃ by means of medical mass spectrometry.
No changes were seen on the subcutaneous tissue pO₂ and pCO₂.
Regional subcutaneous tissue perfusion volume was calculated at 22.57±2.08ml/100g/min (SD=4.45, n=20, p<0.05) with Na₂SO₄·NaHCO₃ bathings which was comparable to that of tap water bathing 20.85±3.56ml/100g/min, (SD=6.71, n=16, p<0.05).
Our preliminary data of the following study indicate that the effect of warming with Na₂SO₄·NaHCO₃ bathings is due possibly to some cellular changes in the connective tissue by mild stimulation of bathing, leading to amelioration of defense mechanism in the body; the study will be reported shortly.

The effect of bathing with artificial sodium sulfate on changes in the systolic blood pressure and the level of atrial natriuretic polypeptide (ANP) in plasma or atrium of normotensive male rats was studied. The following results were obtained:
1) As a result of bathing for 20 minutes at a temperature of 37°C, the systolic blood pressure lowered and the plasma ANP level decreased. The blood pressure lowered most clearly after artificial sodium sulfate bathing at a prescribed concentration (p<0.5), while the plasma ANP level decreased significantly after plain water bathing (p<0.01).
2) The atrial ANP level showed no significant change. Presumably the reason was that the quantity of atrial ANP was so large that it was not affected by fluctuations in the peripheral ANP level.
3) The temperature and duration of bathing, the concentration of bath salts, and other factors might also influence the plasma ANP level.
These results suggest that the artificial sodium sulfate bathing lowers the blood pressure by preventing heat radiation from the skin and by delicate regulatory mechanisms on ANP secretion.

The effects of bathing with artificial sodium sulfate on the systolic blood pressure and the level of atrial natriuretic peptide (ANP) in plasma and or in atrium of spontaneously hypertensive rats (SHR) were studied. The following results were obtained:
1) As a result of bathing for 20 minutes at a temperature of 37°C, the systolic blood pressure lowered and the plasma ANP level increased. The blood pressure lowered with increasing concentration of sodium sulfate (p<0.01).
2) The plasma ANP level in a standing position for 20 minutes decreased than in a normal position.
3) The plasma ANP level in SHR was higher and increased more clearly by bathing, compared to the previous results in normotensive rats (WKA). The blood pressure lowered far more in SHR than in WKA.
4) The atrial ANP level was not significantly influenced by bathing nor by changing the posture.
These results indicate that the artificial sodium sulfate bathing has more potent hypotensive effect than plain water bathing probably due to prevent heat radiation, and affects the blood pressure and the plasma ANP more significantly in SHR than in WKA. In addition, the effects of mild bathing to cardiovascular and neurohumoral systems may modulate directly or indirectly the ANP secretion.

Change of digital blood flow during sodium sulfate bathing was studied using laser Doppler flowmeter. The 10 subjects were divided into two groups; group A and group B. In group A, digital bloood flow was measured in the following order; in the air→plain water→air→sodium sulfate bathing→air, while in group B, in the air→sodium sulfate bathing→air→plain water→air. The temperature of the water was kept at 40°C using thermostat. The 10g of sodium sulfate was dissolved in the 10L of water. In group A, the digital blood flow was 60.2±16.7 in the plain water and 70.6±35.0 in the sodium sulfate water, while in group B, 30.4±12.7 in the sodium sulfate water and 7.36±10.06 in the plain water (P<0.05).
Above results suggest an increase in digital blood flow in the sodium sulfate bathing, although there were great differences by individual and by the order of immersion.

Promethazine-HCl was used to suppress histamine production in the skin by Na₂SO₄·NaHCO₃ bathing, confirming the previous data that the small amount of histamine released as a chemical mediator may have caused the warming effect, as observed in type I allergic reaction.
The skin histamine contents after serial bathings with Na₂SO₄·NaHCO₃ under medication of Promethazine-HCl for 3 weeks were significantly reduced compared with that of tap water (p<0.05).
The skin histamine produced by physical stimulation of Na₂SO₄·NaHCO₃ bathing was suppressed with H₁-blocker (Promethazine), verifying that the warming effect with Na₂SO₄·NaHCO₃ bathing was caused by histamine released as a chemical mediator, as observed in type I allergic reaction.

A study was made on 15 healthy subjects to evaluate the efficacy of water immersion with commonly used raw materials on skin elasticity, viscoelasticity and hydration of stratum corneum.
Samples used in this study included 30, 60, 90g of sodium hydrogen carbonate and 60g of bath preparation containing 90% in weight of sodium hydrogen carbonate (Cool Bathcrin^®). These samples were dissolved into 200l of plain water kept at a temperature of 41°C. The duration of each bathing was 5min.
Skin elasticity (skin distensibility), skin viscoelasticity and hydration of stratum corneum improved in all types of water immersion including plain water immersion. The skin distensibility, viscoelasticity and hydration state showed a statistically significant increase after water immersion with sodium hydrogen carbonate as compared with those before water immersion. In the plain water immersion group, no significant differences were observed between the values before and after water immersion with the exception of skin hydration. However, a significantly higher rate of increase in skin hydration was observed in the groups of water immersion with sodium hydrogen carbonate as compared with the plain water immersion.
The above results show that alkaline salt, especially sodium hydrogen carbonate, improves skin distensibility, viscoelasticity, and hydration state. Furthermore, we recommend sodium hydrogen carbonate as one of the most useful components of bath preparation because it provides the suppleness, freshness, and smoothness of stratum corneum.

We investigated the effects of bathing with bath preparation (sodium sulfate, sodium chloride, 30g/200l) on the thermal preservability in healthy volunteers. We also investigated these effects on the antioxidative defense system in patients with vibration syndrome (VS). In these investigations, we measured the activities of erythrocyte superoxide dismutase (SOD).
After immersion at 41°C for 5min, forearm skin temperature, photoplethysmograph, and transepidermal water loss increased significantly as compared with those after bathing in a plain water.
After bathing for 4 weeks at around 40°C for 10min, activities of erythrocyte SOD increased significantly.
These data indicate that bathing with the bath preparation has a stronger effect on thermal preservability in healthy volunteers and activation of the antioxidative defense system in patients with vibration syndrome due to a significant increase in activities of erythrocyte SOD.

The effects of artificial sodium sulfate bathing on cardiopulmonary and neurohumoral systems as compared to plain water bathing were studied on five healthy subjects. The results of bathing tests made for 10 minutes at 42°C were as follows:
1) The body surface temperature was higher in three of the five subjects in artificial sodium sulfate bathing than in plain water bathing. The forehead temperature of all subjects in artificial sodium sulfate bathing was higher than in plain water bathing (p<0.05: at 17, 18min. after bathing). The change in oral temperature also showed the same tendency (p<0.05: at 27min. after bathing).
2) The frequency of respiration was less in artificial sodium sulfate bathing than in plain water bathing. Although the heart rate decreased during artificial sodium sulfate bathing as compared to the case of plain water bathing, a clear difference was not observed after bathing. The systolic blood pressure in four of the five subjects decreased in artificial sodium sulfate bathing compared to plain water bathing. One subject, who exhibited low blood pressure before bathing, was restored to his normal blood pressure after artificial sodium sulfate bathing. The sysytolic blood pressure was lower in artificial sodium sulfate bathing than in plain water bathing. (p<0.03: at 20min. after bathing).
3) The serum levels of noradrenalin, adrenalin, serotonin, ADH, renin, aldoster-one, cortisol, β-endorphine, Na⁺, K⁺, and Cl^- showed no significant differences between the two types of bathing.
4) All subjects felt increased warmth and smoothness of the skin after the artificial sodium sulfate bathing compared to plain water bathing.
The above results suggest that the artificial sodium sulfate bathing is superior to plain water bathing in maintaining body temperature, decreasing blood pressure, and feeling (i. e., body warmth and skin texture) after bathing. These effects result from not only the direct action on the skin but also the indirect action due to absorption of the substance through the skin by the mechanism of artificial sodium sulfate bathing.