Cytoprotection against apoptosis following an acute bout of exertional heat stress

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TypePresentation
Proceedings titleMedicine and Science in Sports and Medicine
Conference53rd Annual Meeting of the American College of Sports Medicine (ACSM), May31st-June 3nd, 2006, Denver, Colorado
ISSN0195-9131
Volume38
Issue5 Suppl.
PagesS308S308
AbstractInducible heat shock protein (HSP) 72 expression in circulating CD14⁺ monocytes has been found to protect against heat induced cellular apoptosis during exhaustive heat stress. PURPOSE: The purpose of this study was to examine whether the cytoprotective effects seen during exhaustive heat stress impact intracellular HSP72 expression and cellular apoptosis upon subsequent exposures to in vitro heat shock. METHODS: Six untrained men (VO₂peak= 42 ± 1 mL·kg·mm¹) walked at 4.5 km-h¹ with 2% elevation in a climatic chamber (40°C; 30% R.H.) wearing military biological and chemical protective clothing until exhaustion when rectal temperature was 39.07 ± 0.11 °C. Venous blood samples were collected at baseline (prior to heat stress), 24hr and 1-week post exposure. Baseline whole blood was analyzed immediately by flow cytometry for spontaneous HSP72 and Annexin-V immunofluorecence staining in CD14⁺monocytes. Similar analyses were performed at each sampling point following in vitro heat shock (42°C, 2 hr). RESULTS: Intracellular HSP72 expression and cellular apoptosis increased significantly from baseline following in vitro heat shock. In vitro heat shock 1-week post exposure produced a significant increase in the number of CD14⁺ monocytes expressing intracellular HSP72 (0.41 ± 0.04 ×10⁹ cells) compared to the baseline heat shocked sample (0.32 ± 0.05 ×10⁹ cells). Furthermore, the significant increase in HSP positive monocytes was accompanied by a significant decrease in cellular apoptosis 1-week post exposure (16.9 ± 2.45 vs. 23.85 ± 3.34%). CONCLUSIONS: These findings suggest that a single bout of heat stress may confer cytoprotection against heat-induced apoptosis via increased HSP72 expression up to 1-week post trial. These results have implications for experimental designs involving repeated heat exposures, given that longer than one week between trials may be necessary to return to the initial baseline state.
Publication date
PublisherAmerican College of Sports Medicine / Wolters Kluwer
LanguageEnglish
Peer reviewedYes
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NPARC number23001428
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Record identifier4228e995-6301-4654-9845-7a23a16cfa50
Record created2017-02-03
Record modified2017-02-28
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