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Intracellular protein destroying and impairment of their synthesis result in disturbance of cell homeostasis and can lead to cell death. Counteracting these changes the cell induces synthesis of stress proteins among others. Physical exercise has stress attributes, especially if it is a long-lasting and intensive one. It can be assumed that this will bring about an intensification of stress protein expression what was experimentally confirmed. However the significance of this reaction is not fully clear taking into account the variety of functions the stress protein act in the organism. Stress proteins, called also heat shock proteins (HSP) display mainly the enzymatic function used in a direct protection against negative effects of stress. Taking into account their molecular weight one can distinguish two main groups of HSP, the low-molecular and high-molecular ones. HSPs belonging to the low-molecular group act mainly as chape- rons and facilitate the degradation of destroyed proteins. Some of them, as HSP27 and HSP40, enhance the protective potential of other stress proteins. In high-molecular group one can distinguish HSP60, HSP70 and HSP90. As the mostly known and important for humans is HSP70. Stress proteins of this group act against protein aggregation and refolding of denaturized and non-native proteins, and in remo- ving them out of the cell. They act as chaperons of polypeptides synthesized along ribosomes and participate in protecting mechanisms against negative influences of stressors on intracellular processes. Main role of HSP90 is a cooperation in the regulation of cytoskeleton function, and HSP110 is functional- ly related to HSP70. The activity of muscle fibers is performed against a background enclosing influences of numerous mechanical and physiological stressors. During this activity there appear various intracellu- lar changes having adaptative value. It has been shown that muscular activity particularly in changes of HSP27, HSP72 and HSP73 amounts. During the muscular activity there appear preliminary signs of reactive stress where the reactive oxygen species act as second messengers. They influence upon the gene expression, especially upon the transcription factor NFκB being an apoptosis induction factor. In higher concentrations the reactive oxygen species destroy cell structure giving the appearance of TNFα and apoptosis, or an enhancing of Ca2+ concentration in sarcoplasm with the activation of endonuclease, resulting finally in necrosis. The HSP induction is in this situation a part of anti-oxidant defense strategy, acting as mitochondrial protection, and inducing leukocytosis and activating anti-inflammatory cytokines. The course of the above reactions is determined by the character of exercise, its intensity and performing time, and they are probably a part of mechanisms resulting in work adaptation.

The Editorial Board
Andrzej Łukaszyk - przewodniczący, Zofia Bielańska-Osuchowska, Szczepan Biliński, Mieczysław Chorąży, Aleksander Koj, Włodzimierz Korochoda, Leszek Kuźnicki, Aleksandra Stojałowska, Lech Wojtczak

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