Synthesis of 70K stress protein by human leukocytes: effect of exercise in the heat.
To determine whether reinduction of 70,000-Da (70K) stress protein synthesis could be used as an assay for thermal history and/or cellular levels of 70K stress protein in hyperthermic humans, leukocytes were obtained before and after 2 h of exercise and then incubated at 37 or 41 degrees C. Five healthy males completed 2 h of treadmill exercise consisting of running at 4-6 km/h for 30-45 min followed by 75-90 min of walking up a 2-10% grade. This exercise bout was performed by two subjects in hot (46 degrees C, 15% relative humidity) and by five subjects in cooler (30 degrees C, 40% relative humidity) environmental conditions. Exercise resulting in rectal temperature (Tre) less than 40 degrees C did not alter the amount of 70K stress protein synthesized by leukocytes incubated at 41 degrees C. In contrast, exercise resulting in Tre greater than 40 degrees C reduced the amount of 70K stress protein synthesized by leukocytes incubated at 41 degrees C. A protein immunoblot, probed with an antibody specific for the inducible 72K stress protein, showed that the reduction of 35S-labeled 70K stress protein in these postexercise leukocyte samples occurred without marked elevations of this protein. In vitro incubation of human leukocytes at 40 degrees C for 15-120 min reduced, in a time-dependent manner, the amount of 70K stress protein synthesized during a subsequent 41 degrees C heat stress. This reduction of 70K stress protein synthesis in 41 degrees C-treated leukocytes was abolished when cycloheximide was present during the 40 degrees C preincubation.(ABSTRACT TRUNCATED AT 250 WORDS)
Ryan
A J
AJ
Department of Exercise Science, University of Iowa, Iowa City 52242.
Gisolfi
C V
CV
Moseley
P L
PL
D000328:Adult; D015444:Exercise / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000097:blood*; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D066298:In Vitro Techniques; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D013312:Stress, Physiological / Q000097:blood
D006360:Heat-Shock Proteins