Effect of Hot Fomentation on Plasma HSP70 Levels and Body Temperature

Objective: Our previous study reported that thermal stimulation on thigh muscle in vivo and skeletal muscle-derived cell (SMDC) in vitro favorably changed plasma proteins and several gene expression, respectively, to prevent atherosclerotic cardiovascular disease (ASCVD). In our previous in vitro experiment using transcriptome, hot stimulation caused a slight decrease in SMDC density, associated with higher gene expression of apoptosis-related factors as well as HSP70. In the present study, plasma HSP70 was compared before and after hot fomentation methods as a marker of heat stress. Furthermore, skin temperature was measured to assess whether the hot effect was local or systemic.

Method: Subjects were volunteers of 3 men and 7 women aged 21.8 ± 1.31 (mean ± SD). Hot fomentation consisted of four types: hot towels, hot packs, red bean bags, and thermal sheets. Plasma HSP70 concentration was determined by ELISA. Skin temperature was measured by an infrared thermometer.

Results: Plasma HSP70 concentration was significantly reduced by thermal loading using hot towels (pre: 18.46 ± 6.55 vs. post: 14.7 ± 6.66 ng / ml, p = 0.011), but not by those using the other 3 types. Thermal stimulated thigh skin temperature in the opposite side of the hot fomentation was significantly increased by hot towels, hot packs and red bean bags. There was no significant change in axillary temperature.

Conclusion: These results suggest that thermal sheets might not cause heat stress at least in this condition. Hot towels, hot packs and red bean bags provide systemic thermal effect. Further evaluation is required for safe and effective application of hot fomentation to ASCVD prevention.