Medical Hydrology and Balneology: Environmental Aspects

Omega-6-eicosanoid may be involved in the
cutaneous vasodilation mechanism of the rat
bathing in CO2-rich water
Hashimoto M 1) , Kitao N (2) ,Yamamoto N (3)
(1) Teikyo University of Science. Adachi.Tokyo, Japan
(2) Asahikawa Medical UNiversity. Asahikawa. Hokkaido, Japan
(3) Japan Red Cross Hokkaido Colllege of Nursing. Kitami. Hokkaido, Japan
mhashi@ntu.ac.jp
Introduction and Objectives
Bath water of high concentration CO2 (about 1000 ppm) evokes comparable
physiological responses to natural CO2-hot-spring water, which is the local responses
(e.g., a blood flow increase, a vasodilation, and a reddening in the skin in
bathwater) and the global responses (e.g., a decrease in heart rate and blood catecholamine
level, and a blood pressure stabilization). Among these reactions to the
CO2-water, reddening of the skin is a remarkable reaction evoked within a few
minute of immersion. Though the skin flush is not obvious in skin of the experimental
animals, the skin vasodilation is detectable instead.
Though the hypercapnea caused vasodilation is well known, the underlying
physiological mechanism remains still obscure. In this study, we investigated the
possible mediators of skin vasodilation that is evoked by bathing with the CO2water
in experimental animals.
Materials and Methods
A series of study was permitted by the animal experiment ethical committee of
Teikyo University of Science, and was conducted according to the guideline of the
animal experiment approved by the Physiological Society of Japan. Male Wistar
rats (12-21 weeks, 340±60 g) were anesthetized by Urethane (1~1.5 g/kg, ip),
fleeced with cut machine, equipped with probes for measurements of the rectal and
skin temperatures and with a laser Doppler probe for measurement of the skin tissue
blood flow. The CO2-water (CO2 ≥ 1000 ppm) was made with an artificial CO2hot
spring maker (MRE-Spa, Mitsubishi Rayon Cleansui, Tokyo). Rats were immersed
into the tap-water (30 ºC) or the CO2-water of same temperature in head out
position for 30 min.
Results
Intravenous infusion of indomethacine (10 mg/kg) inhibited skin vasodilatation
by CO2-water immersion, a nitric oxide-inhibitor (L-NAME) infusion had no
effect.
Balnea
2012, núm. 6, 311-312
311
ISBN: 978-84-669-1887-0
978-84-669-3482-4