Changes of HSP72-expression in leukocytes are associated with adaptation to exercise under conditions of high environmental temperature.

Overexpression of the heat shock protein HSP72 provides thermotolerance. We asked if two consecutive endurance runs 1 week apart (CR1, CR2) and additional environmental heat stress affect HSP72-expression in leukocytes of nonheat-acclimated endurance athletes. Twelve subjects were allocated randomly into two groups. Group HH completed both runs at 28 degrees C ambient temperature, and group NH performed CR1 at 18 degrees C and CR2 at 28 degrees C. HSP72-expression was determined by flow cytometry and RT-PCR before and 0, 24, and 48 h after exercise. Additionally, post-exercise cells were exposed to in vitro heat shock (HS; 2 h, 42 degrees C). The prolonged, high HSP72 protein level after CR1 in HH compared with NH may reflect thermotolerance induced by endurance exercise at high ambient temperature. Adaptation of cardiocirculatory/thermoregulatory capacity after CR2 in HH went along with a more rapid down-regulation of HSP72 compared with CR1. HSP72 mRNA demonstrated temperature-related changes after exercise. The reduced HS response in vitro after CR2 may represent exercise-related adaptation mechanisms. HSP72 concentrations in leukocytes may indicate previous exercise- and temperature-related stress conditions and adaptation in immunocompetent cells.