Warm SPA-induced hyperthermia confers protection to rats against airway inflammation evoked by capsaicin and substance P.

Solus par aqua (SPA) is a traditional health care therapy. Warm SPA may enhance immunity and cellular defense to protect body against diseases. The present study investigated whether the warm SPA could confer protection to neurogenic inflammation in rats. The rats were immersed in water where the body core temperatures were maintained at hyperthermia (41.5 degrees C) or normothermia (37 degrees C) for a period of 15min. After SPA for 1 or 6 days, neurogenic inflammation was induced by intravenous injection of capsaicin (90microg/kg) or substance P (SP; 3microg/kg). The plasma leakage and arterial pressures in rats after neurogenic inflammation were monitored. The extent of capsaicin- or SP-induced plasma leakage and hypotension was significantly attenuated in rats on day 1 after SPA hyperthermia. However, such resistance to neurogenic inflammation was not found on day 6 after hyperthermia. Western blotting analysis showed that the expression of heat shock protein 72 (HSP 72) in the trachea on days 1 and 2 after hyperthermia was 9.61-fold and 6.66-fold, respectively, of that in normothermia. Afterwards, the hyperthermia-induced HSP 72 upregulation gradually declined in a time-dependent manner. Thus, SPA hyperthermia may protect rats against neurogenic inflammation through modulation of HSP expression.