Phthalides and ligustilide in Senkyu extract and limonene and fravonoids in Chimpi extract have been reported to have strong vasodilation effects.
In the present study the circulatory effects of Senkyu and Chimpi extract (crude drug extract) were studied as bath agent in 40.0°C bath water (Senkyu ext. 224mg and Chimpi ext. 272mg/2001). Thirteen healthy men (36.2±5.8 years old) took a bath at 40.0°C for 10 min with and without (only with flavor and dye) crude drug extract and the circulatory effects were followed for 30 min after bathing.
Heart rate and cardiac output were increased equally by 10 min bathing either with or without crude drug extract. Although systolic blood pressure was slightly increased during bathing, diastolic blood pressure and total peripheral resistance were significantly decreased during and after bathing with and without crude drug extract. Forehead skin blood flow and sublingual temperature were significantly increased during bathing, and remained at higher level for 10-30 min after bathing with crude drug extract. Venous blood pO₂ and pH were significantly increased and pCO₂ was decreased equally with and without crude drug extract. Plasma NE was significantly increased by bathing with crude drug extract.
Bath agent with Senkyu and Chimpi extract are considered favorable as bath agent to keep high skin blood flow and sublingual temperature probably due to its vasodilating effects.

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.

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.

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.

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.

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.

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.

The warming effect following serial bathing in the water containing Na₂SO₄·NaHCO₃ was studied in rabbits by mass spectrometry.
Rabbits, weighing about 2kg, were placed in a bath containing Na₂SO₄·NaHCO₃ (33g/20l) at 36-37°C for 20 minutes every day for 3 weeks.
By mass spectrometry, the subcutaneous tissue perfusion rate was calculated on the basis of changes in the partial pressure of Argon injected on diffusion membrane of the sensor catheter.
The mean subcutaneous pCO₂ was 46.6±14.6mmHg in the Na₂SO₄·NaHCO₃ bath group and 28.8±6.7mmHg in the control tap water group; the tissue perfusion rate in these two groups was 26.78±6.45ml/100g/min and 20.32±7.15ml/100g/min, respectively.
The warming effect of Na₂SO₄·NaHCO₃ bathing is thought to be derived from increased metabolism and micro-circulation dynamics resulting from dermal stimulation by Na₂SO₄·NaHCO₃.

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.