Role of Hsp72 and norepinephrine in the moderate exercise-induced stimulation of neutrophils' microbicide capacity

The influence of a single session of moderate exercise (45 min at 55% of VO2 max) performed by young sedentary men (23-25 years old) on the microbicidal capacity of neutrophils was compared by using both direct (killing of phagocytosed Candida albicans) and indirect (superoxide anion production measured by NBT reduction) techniques. In addition, the role of norepinephrine and heat shock protein (Hsp) 72 in the modulation of microbicide capacity of neutrophils was evaluated during the protocol of exercise and recovery period (24 h). No significant changes were found in the superoxide production after exercise. However, immediately after exercise there was an increase in the destruction of C. albicans, which remained higher than basal values 1 day later. This behaviour was similar to the changes found in the serum extracellular Hsp72 concentrations (an increase after exercise that remained higher than basal values 24 h later). In vitro, the raised physiological concentration of Hsp72 after exercise also increased the microbicide capacity of neutrophils with respect to controls and the values induced by the basal concentration of the protein. This indicates that Hsp72 is participating as a "stress mediator" of the stimulated microbicide activity during moderate exercise. However, norepinephrine is not mediating the increased killing of C. albicans during exercise.