Heat and exercise acclimation increases intracellular levels of Hsp72 and inhibits exercise-induced increase in intracellular and plasma Hsp72 in humans.
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.
Magalhães
Flávio de Castro
Fde C
Laboratory of Biochemistry of Physical Activity, University of São Paulo, São Paulo, Brazil.
Amorim
Fabiano Trigueiro
FT
Passos
Renata L Freitas
RL
Fonseca
Michele Atalla
MA
Oliveira
Kenya Paula Moreira
KP
Lima
Milene Rodrigues Malheiros
MR
Guimarães
Juliana Bohen
JB
Ferreira-Júnior
João Batista
JB
Martini
Angelo R P
AR
Lima
Nilo R V
NR
Soares
Danusa Dias
DD
Oliveira
Edilamar Menezes
EM
Rodrigues
Luiz Oswaldo Carneiro
LO
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
D050884:HSP72 Heat-Shock Proteins