Mild endotoxemia, NF-kB translocation, and cytokine increase during exertional heat stress in trained and untrained individuals


  1. Selkirk, G.A.
  2. McLellan, T.M.
  3. Wright, H.E.
  4. Rhind, S.G.
Corporate Authors
Defence R&D Canada - Toronto, Toronto ONT (CAN)
This study examined intranuclear NF-kB translocation in circulating blood leukocytes during exertional heat stress (EHS). Twenty-three male subjects were divided into trained (TR, n=12, = 70 ± 2 mL•kgLBM-1•min-1) and untrained (UT, n=11, = 50 ± 1 mL•kgLBM-1•min-1) groups prior to walking at 4.5 km•h-1 with 2% elevation in a climatic chamber (40°C; 30% R.H.), wearing protective clothing until specific end-point criteria were attained. Venous whole blood samples were collected at baseline and 0.5°C rectal temperature increments, including 38.0°C, 38.5°C, 39.0°C, 39.5°C and 40.0°/exhaustion (Exh), and then analyzed immediately by flow cytometry. Baseline and Exh samples were further stimulated with lipopolysaccharide (LPS) and cultured in vitro in a water-bath (37°C, 30 min, 100ng/mL) prior to acquisition. Phenotypic determination of natural killer (NK) lymphocyte frequency was also determined. Comparison of the changes in peripheral blood mononuclear cell (PBMC) (minus NK) counts revealed a greater inflammatory activation for a given level of thermal strain below 39.0°C in UT compared to TR. In addition, a transient peak in PBMC NF-kB protein content was observed prior to Exh at 38.5°C in UT and 39.5°C in TR. In contrast, TR polymorphonuclear neutrophils exhibited a hyper-reactive response throughout the trial. Alterations in LPS-induced NF-kB protein content were also observed post EHS. These combined findings demonstrate an increase in NF-kB translocati

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Peripheral blood mononuclear cells, polymorphonuclear neutrophils, flow cytometr
Report Number
DRDC-TORONTO-SL-2007-175 — Scientific Literature
Date of publication
18 Jun 2008
Number of Pages
Reprinted from
American Journal of Physiology: Regulatory, Integrative and Comparitive Physiology, vol 295, 2008, p R611-R623
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