HSP70 EXPRESSION IN HUMAN SKELETAL-MUSCLE AFTER EXERCISE

Prolonged exercise of a sufficiently high intensity is thought to crea te physiological stress and to disturb cellular homeostasis. ultimatel y inducing cellular adaptations which enable the organism to better de al with any future exercise challenge. Hear shock proteins (hsp) are e xpressed when cells are exposed to different types of stress. In this study, we have investigated whether the expression of the heat inducib le form of hsp70 is increased in human skeletal muscle cells after a s ingle bout of exercise. Five untrained subjects performed an exercise bout at their individual anaerobic threshold for 30 min on a treadmill . Hsp70 mRNA concentration was significantly increased by a factor of four at 4 min post-exercise. Similarly high levels were also observed 30 min and 3 h after the end of exercise. Hsp70 protein concentration, on the contrary. did not change within 3 h after cessation of exercis e. Thus, a single exercise bout in humans is able to increase the stea dy state concentration of hsp70 mRNA. but is probably not sufficient t o have an effect on the already high basal level of its protein. The a nalysis of hsp70 mRNA is potentially useful as a method to detect stre ss in tissues with a high basal level of heat shock proteins.