title: Heat and exercise acclimation increases intracellular levels of Hsp72 and inhibits exercise-induced increase in intracellular and plasma Hsp72 in humans.
abstract: In order to verify the effects of heat and exercise acclimation (HA) on resting and exercise-induced expression of plasma and leukocyte heat shock protein 72 (Hsp72) in humans, nine healthy young male volunteers (25.0 ± 0.7 years; 80.5 ± 2.0 kg; 180 ± 2 cm, mean ± SE) exercised for 60 min in a hot, dry environment (40 ± 0°C and 45 ± 0% relative humidity) for 11 days. The protocol consisted of running on a treadmill using a controlled hyperthermia technique in which the work rate was adjusted to elevate the rectal temperature by 1°C in 30 min and maintain it elevated for another 30 min. Before and after the HA, the volunteers performed a heat stress test (HST) at 50% of their individual maximal power output for 90 min in the same environment. Blood was drawn before (REST), immediately after (POST) and 1 h after (1 h POST) HST, and plasma and leukocytes were separated and stored. Subjects showed expected adaptations to HA: reduced exercise rectal and mean skin temperatures and heart rate, and augmented sweat rate and exercise tolerance. In HST1, plasma Hsp72 increased from REST to POST and then returned to resting values 1 h POST (REST: 1.11 ± 0.07, POST: 1.48 ± 0.10, 1 h POST: 1.22 ± 0.11 ng mL(-1); p < 0.05). In HST2, there was no change in plasma Hsp72 (REST: 0.94 ± 0.08, POST: 1.20 ± 0.15, 1 h POST: 1.17 ± 0.16 ng mL(-1); p > 0.05). HA increased resting levels of intracellular Hsp72 (HST1: 1 ± 0.02 and HST2: 4.2 ± 1.2 density units, p < 0.05). Exercise-induced increased intracellular Hsp72 expression was observed on HST1 (HST1: REST, 1 ± 0.02 vs. POST, 2.9 ± 0.9 density units, mean ± SE, p < 0.05) but was inhibited on HST2 (HST2: REST, 4.2 ± 1.2 vs. POST, 4.4 ± 1.1 density units, p > 0.05). Regression analysis showed that the lower the pre-exercise expression of intracellular Hsp72, the higher the exercise-induced increase (R = -0.85, p < 0.05). In conclusion, HA increased resting leukocyte Hsp72 levels and inhibited exercise-induced expression. This intracellular adaptation probably induces thermotolerance. In addition, the non-increase in plasma Hsp72 after HA may be related to lower stress at the cellular level in the acclimated individuals.
authors.affiliation: Laboratory of Biochemistry of Physical Activity, University of São Paulo, São Paulo, Brazil.
authors.forename: Flávio de Castro
authors.initials: Fde C
authors.lastname: Magalhães
authors.forename: Fabiano Trigueiro
authors.initials: FT
authors.lastname: Amorim
authors.forename: Renata L Freitas
authors.initials: RL
authors.lastname: Passos
authors.forename: Michele Atalla
authors.initials: MA
authors.lastname: Fonseca
authors.forename: Kenya Paula Moreira
authors.initials: KP
authors.lastname: Oliveira
authors.forename: Milene Rodrigues Malheiros
authors.initials: MR
authors.lastname: Lima
authors.forename: Juliana Bohen
authors.initials: JB
authors.lastname: Guimarães
authors.forename: João Batista
authors.initials: JB
authors.lastname: Ferreira-Júnior
authors.forename: Angelo R P
authors.initials: AR
authors.lastname: Martini
authors.forename: Nilo R V
authors.initials: NR
authors.lastname: Lima
authors.forename: Danusa Dias
authors.initials: DD
authors.lastname: Soares
authors.forename: Edilamar Menezes
authors.initials: EM
authors.lastname: Oliveira
authors.forename: Luiz Oswaldo Carneiro
authors.initials: LO
authors.lastname: Rodrigues
mesh_terms: D000064:Acclimatization; D000328:Adult; D001831:Body Temperature; D015444:Exercise; D050884:HSP72 Heat-Shock Proteins / Q000097:blood* / Q000378:metabolism; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D007962:Leukocytes / Q000276:immunology / Q000378:metabolism; D008297:Male; D012044:Regression Analysis; D013546:Sweating / Q000502:physiology
chemical_list: D050884:HSP72 Heat-Shock Proteins