TISSUE-SPECIFIC HSP70 RESPONSE IN ANIMALS UNDERGOING HEAT-STRESS

Heatstroke is a multisystem disorder that can result in death. Activit ies that increase the rate of heat storage predispose an organism to t hermal injury. Using a 72-kDa heat shock protein (HSP72) as a marker o f thermal injury, we determined 1) which organs synthesize HSP in anim als after hyperthermia and 2) whether a high heating rate (HHR) result ed in more HSP72 than a low heating rate (LHR). Rats were assigned to either control, HHR (0.166 degrees C/min), or LHR (0.045 degrees C/min ) groups. Heat exposure ended when colonic temperature (T-c) reached 4 2 degrees C. Total time in the heat and thermal load (measured as the time an animal maintained a T-c > 40.4 degrees C) were significantly l ower in HHR compared with LHR animals. Hyperthermia resulted in a tiss ue-specific increase in HSP72 in the liver, small intestine, and kidne y, but not in the brain or quadriceps muscles. In addition, HHR animal s showed significantly greater accumulation of HSP72 in the liver comp ared with animals in the LHR group. Thus HSP72 synthesis is tissue spe cific at high physiological temperatures and may identify a critical t arget tissue susceptible to early thermal damage.