酸性泉浴における硫酸イオンの皮膚透過性

抄録

Of late many studies have been reported upon the permeability of the skin to sulfateions in spring waters.
Kusatsu Hot Springs (hydrogen sulfide-containing acid springs, pH at 1.5-1.7, SO₄ 1.1-3.2g/kg) have a peculiar way of bathing, that is, so-called “Jikan-yu” (or time-limit bath). Bathers take thermal bath under the command of a bath master at a high temperature of 43-48°C, 4 times a day, for 3 minutes. This custom has been known from old days, and is still today kept by some bathers, though day by day diminishing in number, as a home cure for chronic diseases. As a result of such spa treatment many of the bathers would come to suffer from an acid spring dermatitis in the axillary or genitofemoral regions. And increases in bactericidal activity of the blood, phagocytosis of leucogtes, PBI, urinary excretion of 17-KS and estrogen, etc. were proved.
To give a clue to solve the mechanism of these strongly stimulative actions of acid spring bath the author intended to investigate the percutaneons absorption and excretion of sulfate in the spring waters by using S³⁵-labeled sulfate.
I. Absorption of Sulfate through the Mouse Skin
After bathing in with S³⁵O₄ labeled spring waters under varing conditions, mice were killed and their skins were removed. The carcasses were ignited to ashes, dissolved in HCl and then precipitates were obtained by adding BaCl₂.
Radioactivity measurement of S³⁵ in each sample indicated that the longer the duration of bath and the higher the temperature of bath-water was, the more the amount of absorbed sulfate increased.
No significant difference was found, however, concerning the percutaneous absorption between the controls and the animals that had been bathed for three weeks in non-radioactive spring waters. It did not coincide with previously reported findings that the frequent baths had decreased the ionic absorption from bath-water. A presumptive explanation for it may he that a stimulative effect of acid spring might have produced some change in the skin through repeated bathing which might result in an increase of the percutaneous sulfate absorption. Indeed with animals which got burnt, sulfate absorption proved to increase remarkably. This fact suggests a probable increase in permeability of the impaired skin.
II. Excretion of Sulfate through the Rabbit Skin
Wet dressing soaked with bath-water in question was applied to the abdominal slain of each rabbit, to which an isotonic solution of S³⁵-labeled Na₂SO₄ was intravenousiy administered beforehand.
The percutaneous excretion of S³⁵ was confirmed. But it failed in this study to prove significant difference in sulfate excretion, if there be any, among soaking fluids such as fresh water, natural spring water, and H₂SO₄ solution (pH 1.7).
III. Absorption of Sulfate through the Human Skin
Test subjects, including both sexes, were divided into three groups according to the skin conditions, that is:
(A) Five persons with manifest acid spring dermatitis: flush, crosion and secretion in the genitofemoral or axillary regions.
(B) Three persons without recognizable dermatitis in spite of their repeated thermal hathings for one month or over.
(C) Three persons as control subjects, who had not bathed in the spring for some time before the experiment.
Every one of them was applied a wet dressing soaked with the labeled spring waters to the inflammatory part, or otherwise to the corresponding region during thirty to sixty minutes. Then, their 36 hour-urines were collected and radioactivity of the excreted S³⁵ was measured.
Elimination of S³⁵ in the urines from the dermatitis group was strikingly increased as compared with that from the control group—roughly one thousand times on the average.
The percutaneously absorbed SO₄