title: No effects of acclimation to heat on immune and hormonal responses to passive heating in healthy volunteers.
abstract: Heat acclimation results in whole body-adaptations that increase heat tolerance, and might also result in changed immune responses. We hypothesized that, after heat acclimation, tumor necrosis factor alpha, interleukin 6 and the lymphocyte count would be altered. Heat acclimation was induced in 6 healthy men by 100 min of heat exposure for 9 days. Heat exposure consisted of (1) 10 min of immersion up to chest-level in water at 42°C and (2) 90 min of passive heating by a warm blanket to maintain tympanic temperature at 37.5°C. The climatic chamber was maintained at 40°C and a relative humidity of 50%. Blood samples were analyzed before and after heat acclimation for natural killer (NK) cell activity, counts of lymphocytes B and T, before and after heat acclimation for peripheral blood morphology, interleukin 6, tumor necrosis factor alpha, and cortisol. A Japanese version of the profile of mood states questionnaire was also administered before and after acclimation. The concentrations of white blood cells, lymphocytes B and T, cortisol, interleukin 6, tumor necrosis factor alpha and NK cell activity showed no significant differences between pre- and post-acclimation, but there was a significantly lower platelet count after acclimation and, with the profile of mood states questionnaire, there was a significant rise in anger after acclimation. It is concluded that heat acclimation by passive heating does not induce alterations in immune or endocrine responses.
authors.affiliation: Department of Physiology, Aichi Medical University School of Medicine, Nagakute, Aichi, Japan. dominika@aichi-med-u.ac.jp
authors.forename: Dominika
authors.initials: D
authors.lastname: Kanikowska
authors.forename: Maki
authors.initials: M
authors.lastname: Sato
authors.forename: Junichi
authors.initials: J
authors.lastname: Sugenoya
authors.forename: Satoshi
authors.initials: S
authors.lastname: Iwase
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Naoki
authors.initials: N
authors.lastname: Nishimura
authors.forename: Yoko
authors.initials: Y
authors.lastname: Inukai
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000328:Adult; D000786:Anger; D001831:Body Temperature; D006358:Hot Temperature; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D007958:Leukocyte Count; D008297:Male; D010976:Platelet Count; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D055815:Young Adult
chemical_list: D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D006854:Hydrocortisone