Study on the adaptation mechanisms to the hot tropical environment in human beings and animals and its application of tropical medicine are the aims in the Department, which was newly established in　１９９４． In collaboration with the Department of Environmental Physiology, the following researches are on going.

Study on long‐term heat acclimatization in tropical inhabitants
　　Core temperature, skin temperatures, local sweat rates, and metabolic rate during heat load or exercise and Ach sensitivity of the sweat gland are compared between Japanese and tropical inhabitants （Thai and Africans）. It has been revealed that in a hot environment, tropical inhabitants can efficiently regulate their body temperature with less amount of sweat compared to Japanese, because of their excellent dry heat loss ability（conduction, convection and radiation） and suppression of ineffective sweating which drips off the skin. Suppressed sweating in tropical residents is attributed to adaptation in both central（upward shift of threshold core temperature for sweating and suppression of the gain）and peripheral（suppression of Ach sensitivity of the sweat gland）sudomotor mechanisms. This stucy is carried out in collaboration with the Department of Physiology, Chiang Mai University, Thailand.

Study on cross‐adaptation of physical training to heat
　　After a short‐term physical training, heat tolerance is enhanced by the activated sweat response. On the other hand, the athletes who trained for a long time are tolerant to heat, as their sweat response is suppressed. The roles of central and peripheral mechanisms are being investigated.

Study on cellular and molecular heat‐tolerance in temperature sensitive mutant cells
　　The temperature‐sensitive mutant from mouse breast cancer cells, tsFT１０１， is multinuclei when cultured at ３９℃. The induction of thermotolerance and also the induction of heat shock proteins due to pre‐heating at ４５℃ for ３０ min are very little in tsFT１０１ cells cultured at ３９℃.The mechanisms of thermotolerance in cellular and molecular level are under investigation by using this cell line.

Study on cold adaptation in the weak heattolerant animal, pika（Ochotona）
　　The pika（Ochotona）living in the cold areas or high mountains attracts attentions as an animal model of cold adaptation as well as highaltitude adaptation. Th pika is intolerant to heat for lack of efficient heat loss mechanisms, and does not hibernate in winter. To clarify the cold adaptation mechanisms in pikas, physiological studies on atonomic and behavioral thermoreguration, anatomical studies and the field studies in their natural habitats in China and Mongolia are on going.

Comparison of thermal adaptability among tropical, subtropical and temperate subjects
　　We compare the natural environmental adaptability through out the effect of environmental temperature and sunlight on functional, morphological, and organic changes in tropical（Thai）, subtropical （Nepal） and temperate（Japanese）subjects.